Experiments and Observations on the Specific Gravities and Attractive Powers of Various Saline Substances. By Richard Kirwan, Esq. F. R. S.

II. Experiments and Observations on the specific Gravities and attractive Powers of various saline Substances. By Richard Kirwan, Esq. F. R. S. Read November 16, 1780. The doctrine of chymical affinities hath of late received great improvements from the labours of the very excellent Mr. Bergman of Upsal, and the still later researches of Mr. Wentzel; but the order of these attractions has hitherto been the only point attended to by these philosophers, as well as by most preceding chymists: for I know of none, except Mr. Morveau of Dijon, who has thought of ascertaining the various degrees of force of chemical attraction, by which one body acts on various other bodies, or even on the same body in various circumstances. He has, however, so ably shewn the advantages arising from such an inquiry, that I have made it the object of my attention, and bestowed much pains on it for some time past; and have been thereby enabled to determine pretty exactly the proportion of the ingredients of many neutral salts, and the specific gravity of the mineral acids in their purest state, and free from all water. The principles on which these determinations are founded are the following. 1st. That the specific gravity of bodies is as their weight, divided by the weight of an equal bulk of rain or distilled water, this being at present the standard with which every other body is compared. 2dly. That if bodies, specifically heavier than water, be weighed in air and in water, they lose in water part of the weight which they were found to have in air; and that the weight so lost is just the same as that of an equal bulk of water, and consequently that their specific gravity is equal to their weight in air, or absolute weight, divided by their loss of weight in water. 3dly. That if a solid, specifically heavier than a liquid, be weighed first in air, and then in that liquid, the weight it loses is equal to the weight of an equal volume of that liquid; and consequently if such solid be weighed first in air, then in water, and afterwards in any other liquid, the specific gravity of this liquid will be as the weight lost in it by such solid, divided by the loss of weight of the same solid in water. This method of finding the specific gravity of liquids I have found much more exact than that by the areometer, or the comparison of weights of equal measures of such liquids and water, both of which are subject to several inaccuracies. 4thly. That where the specific gravity of bodies is already known, the weight of an equal bulk of water may also be found, it being as the quotient of their absolute weight divided by their specific gravity. This I shall call their loss of weight in water. Hence, where the specific gravity and absolute weight of the ingredients of any compound are known, the specific gravity of such compound may easily be calculated as it ought to be intermediate betwixt that of the lighter and that of the heavier, according to their several proportions: this I call the mathematical specific gravity. But, in fact, the specific gravity of compounds, found by actual experiment, seldom agrees with that found by calculation, but is often greater without any diminu- tion of the lighter ingredient. This increase of density must then arise from a closer union of the component parts to each other than either had separately with its own integrant parts; and this more intimate union must proceed from the attraction or affinity of these parts to each other: I therefore imagined this attraction might be estimated by the increase of density or specific gravity and was proportionable to it, but was soon undeceived. I must also premise, that the absolute weights of many sorts of air have been accurately determined by Mr. Fontana, at whose experiments I was present, the thermometer being at $55^\circ$, and the barometer at $29\frac{1}{2}$ inches, or nearly so. Their weights were as follows: | Cubic inch of common air | - | 0.385 | |--------------------------|---|-------| | Fixed air | - | 0.570 | | Marine air | - | 0.654 | | Nitrous air | - | 0.399 | | Vitriolic air | - | 0.778 | | Alkaline air | - | 0.2 | | Inflammable air | - | 0.03 | OF SPIRIT OF SALT. From the time I first read in Dr. Priestley's Experiments on Air (that inexhaustible source of future discoveries) of the exhibition of marine acid in the form of air, free from water; and that this air, reunited with water, formed an acid liquor in all respects the same as common spirit of salt; I conceived the possibility of discovering the exact quantity of acid in spirit of salt of any given specific gravity, and by means of this the exact proportion of acid in all other acid liquors; for if a given quantity of pure fixed alkali were saturated, first by a certain quantity of spirit of salt, and then by determined quantities of the other acids, I concluded, that each of these quantities of acid liquor must contain the same quantity of acid, and this being known, the remainder being the aqueous part, this also must be known; but this conclusion entirely rested on the supposition that the same quantity of all the acids was requisite for the saturation of a given quantity of fixed alkali; for if such given quantity of fixed alkali might be saturated by a smaller quantity of one acid than of another, the conclusion fell to the ground. This point might, indeed, be in some measure determined by weighing the neutral salts, formed by these acids, when thoroughly dry; but still a source of inaccuracy remained: for if they were exposed to a considerable heat, part of the acid would necessarily be expelled, and more of one acid than of another, and if the heat were not considerable, much of the water of crystallization would remain; so that if the weights were found to be equal, this equality could not be ascribed to equal quantities of acid, but might perhaps arise from a smaller proportion of acid in one of them, and a larger proportion of water, and in another from a larger proportion of acid and a smaller proportion of water; and if the weights were unequal, no certain conclusion could be drawn. To obviate this difficulty I used the following expedient. 1st. I supposed the quantities of nitrous and vitriolic acids, necessary to saturate a given quantity of fixed alkali, exactly the same as that of marine acid whose quantity I determined; and to prove the truth of this supposition, I observed the specific gravity of the spirit of nitre and oil of vitriol I made use of, and in which I supposed, from the trial with alkalies, a certain proportion of acid and water; I then added to these more acid and water, and calculated what their specific gravities should be upon the above supposition, and finding the result to tally with the supposition, I concluded the latter to be exact. The experiments made on the marine acid were as follows. I took two bottles, which I filled nearly to the top with distilled water, of which they contained in all 1399.9 gr. and introduced them successively into two cylinders filled with marine air, which I had obtained from common salt by means of dilute oil of vitriol and heat, in a mercurial apparatus; and this process I renewed until the water had imbibed, in eighteen days, about 794 cubic inches of the marine air. The thermometer did not rise all this time above 55°, nor sink, unless perhaps at night, under 50°, and the barometer was between 29 and 30 inches. This water, or rather spirit of salt, I then found to weigh 1920 gr. that is 520.1 more than before. The quantity of marine air absorbed amounted then to 520.1 gr. I then examined the specific gravity of this spirit of salt, and found it to be 1.225. Its loss of weight in water (that is, the weight of an equal bulk of water) should then be 1567.346 gr. nearly; but it contained only, as we have seen, 1399.9 gr. of water; therefore subtracting this from 1567.346, the remainder (that is, 167.446) must be the loss of 520.1 gr. of marine acid; and consequently the specific gravity of the pure marine acid, in such a condensed state as it is in when united to water, must be \[ \frac{520.1}{167.446} = 3.100. \] But still it might be suspected, that the density of this spirit did not entirely proceed from the mere density of the marine acid, but in part also from the attraction of this acid to water, and though the length of time requisite to make water imbibe this quantity of acid made me judge that the attraction attraction was not very considerable, yet the following experiment was more satisfactory. I exposed 1440 gr. of this spirit to marine air for five days, the thermometer being at 50° or under; it then weighed 1562 gr. and consequently imbibed 122 gr. of marine air; its specific gravity was then 1,253, which agrees exactly with what it should be by calculation. N. B. I have not repeated the whole of these experiments, as they were very tedious; but I began them over again several times before I could ascertain with any precision the quantity of marine air absorbed, as, when the whole of a cylinder full of air was absorbed, it was difficult to stop the bottles so as to prevent any mercury from falling in; and I was obliged every night to fill the cylinders with air, lest if there remained but a small quantity it might be imbibed before morning, and the mercury fall into the bottles. I also made some allowance for the common air which I could not avoid letting into the cylinder with the marine air, as will be very apparent to whoever repeats the experiment. Being now satisfied I had discovered the proportion of acid and water in spirit of salt, I was impatient to find it in other acids also; and for that purpose I took 180 gr. of very strong oil of tartar per deliquium, but of whose specific gravity I can find no note, and found it to be saturated by 180 gr. of spirit of salt, whose specific gravity was 1,225. Now, by calculation it appears, that 180 gr. of this spirit contains 48.7 gr. of acid and 131.3 of water, and hence I drew up the following table. The specific gravity of the strongest spirit of salt, made in the usual way, is, according to Mr. BAUME, 1,187, and according to Mr. BERGMAN, 1,190; but we read in the Paris Memoirs for the year 1700, p. 191, that Mr. HOMBERG passed a spirit whose specific gravity was 1,300; and that made by Dr. PRIESTLEY (see vol. III. p. 275.) must have been about 1,500. Hence we see, that spirit of salt, whose specific gravity is 1,261 or less, has little or no attraction with water, and therefore attracts none from air, and on that account does not heat a thermometer whose ball is dipped in it as spirit of vitriol and spirit of nitre do, as has lately been observed by the Friendly Society of Berlin. This table is not exactly accurate, as I had not in this first experiment found the point of saturation as nicely as was requisite. However, I have not corrected it, as the error is but small, and the proportion may at any time be found by calculation; at least when the specific gravity of this spirit does not exceed 1,253. Whether the mathematical specific gravity and that by observation differ in the higher degrees of specific gravity, I have not examined; but the table is formed on the supposition that they do not. | Marine acid | Water Parts | Specific Gravity | |------------|-------------|-----------------| | | | | | 50 | 1,497 | | | 60 | 1,431 | | | 70 | 1,381 | | | 80 | 1,341 | | | 90 | 1,308 | | | 100 | 1,282 | | | 110 | 1,259 | | | 120 | 1,246 | | | 130 | 1,223 | | | 140 | 1,209 | | | 150 | 1,196 | | | 160 | 1,185 | | | 170 | 1,175 | | | 180 | 1,166 | | | 190 | 1,158 | | | 200 | 1,151 | | | 210 | 1,144 | | | 220 | 1,138 | | | 230 | 1,132 | | | 240 | 1,127 | | | 250 | 1,122 | | | 260 | 1,118 | | | 270 | 1,114 | | | 280 | 1,110 | | | 290 | 1,106 | | | 300 | 1,103 | | | 310 | 1,100 | | | 320 | 1,097 | | | 330 | 1,091 | | | 340 | 1,089 | | | 350 | 1,086 | | | 360 | 1,084 | | | 370 | 1,082 | | | 380 | 1,080 | | | 390 | 1,078 | | | 400 | 1,076 | | | 410 | 1,074 | | Common Common spirit of salt is always adulterated with vitriolic acid, and therefore not fit for these trials. Intending to determine by this experiment the proportion of acid, water, and fixed alkali in digestive salt, as it is called, I took 100 gr. of a solution of a tolerably pure vegetable alkali that had been three times calcined to whiteness, the specific gravity of which solution was 1.097. I also diluted the spirit of salt with different portions of water; the specific gravity of one sort was 1.115, and of another 1.098. I then found that the above quantity of the solution of a vegetable alkali required for its saturation 27 gr. of that spirit of salt whose specific gravity was 1.098, and 23.35 gr. of that spirit of salt whose specific gravity was 1.115. Now, 27 gr. of spirit of salt, whose specific gravity is 1.098, contain 3.55 gr. of marine acid, as appears by calculation. As the principle on which this calculation, by which the proportion of substances in alloy is found, may not be generally known, I shall here mention them in the words of Mr. Cotes. "The data requisite are the specific gravities of the mixture and of the two ingredients. . . . Then, as the difference of the specific gravities of the mixture and the lighter ingredient is to the difference of the specific gravities of the mixture and the heavier ingredient, so is the magnitude of the heavier to the magnitude of the lighter ingredient. Then, as the magnitude of the heavier multiplied into its specific gravity is to the magnitude of the lighter multiplied into its specific gravity, so is the weight of the heavier to the weight of the lighter . . . . Then, as the sum of these weights is to the given weight of either ingredient, so is the weight given to the weight of the ingredient sought." Thus, Thus, in this case, $1,098 - 1,000 = 0.098$ is the magnitude of the heavier ingredient, viz. the marine acid; and, $0.098 \times 3,100 = 0.3038$ the weight of the marine acid; and, on the other hand, $3,100 - 1,098 = 2,002$ the magnitude of the water, and $2,002 \times 1,000 = 2,002$ its weight; the sum of these weights is $2,3058$: then, if $2,3058$ parts of spirit of salt contain $0.3038$ parts acid, $27$ gr. of this spirit of salt will contain $3.55$ acid. In the same manner it will be found, that $23.35$ gr. of spirit of salt, whose specific gravity was $1.115$, contained $3.55$ gr. acid. The point of saturation was pretty accurately found by putting the glass cylinder which contained the alkaline solution on the scale of a very sensible balance, and at the same time weighing the acid liquor in another pair of scales, when the loss of weight indicated the escape of nearly equal quantities of the fixed air contained in the solution; then the acid was gradually added, by dipping a glass rod into it, to the top of which a small drop of acid adhered: with this the solution was stirred, and very small drops taken up and laid on bits of paper stained blue with radish juice. As soon as the paper was in the least reddened, the operation was completed so that there was always a very small excess of acid, for which half a grain was constantly allowed; but no allowance was made for the fixed air, which always remains in the solution; but as, on this account, only a small quantity of the alkaline solution was used, this proportion of fixed air must have been inconsiderable. If an ounce of the solution had been employed, this inappreciable portion of fixed air would be sufficient to cause a sensible error: for I judged of the quantity of fixed air lost by the difference betwixt the weight added to the $100$ gr. and the actual weight of Mr. Kirwan's Experiments, &c. on the specific Gravities of the compound. When this difference amounted to 2,2 gr. then I judged the whole of the fixed air expelled, and found it to be so, as 100 gr. of this alkaline solution, being evaporated to dryness in a heat of 300°, left a residuum which amounted to 10½ gr.; which 10½ gr. contained 2,2 gr. of fixed air, as will hereafter be seen. Hence 8,3 gr. of pure vegetable fixed alkali, free from fixed air and water, or 10,5 of mild fixed alkali, were saturated by 3,55 gr. of pure marine acid, and consequently the resulting neutral salt should, if it contained no water, weigh 11,85 gr.; but the salts resulting from this union (the solution being evaporated to perfect dryness in a heat of 160° kept up for four hours) weighed at a medium 12,66 gr. Of this weight 11,85 gr. were acid and alkali; therefore the remainder, viz. 0,81 of gr. were water; therefore 100 gr. of perfectly dry, digestive salt contain 28 gr. acid, 6,55 water, 65,4 of fixed alkali. I was then curious to compare my experiments with those made by others, but could not find any made with sufficient precision but those of Mr. Homberg in the Paris Memoirs for 1699. However, as to spirit of salt I did not think proper to compare them, as he mentions that his could dissolve gold, and therefore was probably impure. OF SPIRIT OF NITRE. The common reddish brown or greenish spirit of nitre containing, besides acid and water, a certain portion of phlogiston, and being also mixed with some portion of the acid of sea salt, I judged unfit for these trials, and therefore used only the de-phlogisticated sort, which is quite colourless, and resembles pure water in its appearance. This pure acid cannot be made to exist in in the form of air, as Dr. Priestley has shewn; for when it is deprived of water and phlogiston, and furnished with a due proportion of elementary fire, it ceases to have the properties of an acid, and becomes dephlogisticated air; I could not, therefore, determine its proportion in spirit of nitre as I had done that of the marine acid, but was obliged to use another method. 1st. To 1963.25 gr. of this spirit of nitre, whose specific gravity was 1.419, I gradually added 179.5 gr. of distilled water, and when it cooled I found the specific gravity of this mixture 1.389. 2dly. To 1984.5 gr. of this I again added 178.75 gr. of water; its specific gravity was then 1.362. I then took 100 gr. of a solution of fixed vegetable alkali, whose specific gravity was 1.097, the same I had before used in the trials with spirit of salt, and found this quantity of alkali to be saturated by 11 gr. of the spirit of nitre, whose specific gravity was 1.419; and by 12 gr. of the spirit, whose specific gravity was 1.389; and by 13.08 of that, whose specific gravity was 1.362. The quantities here mentioned were the medium of five experiments. I found it necessary to dilute the nitrous acid with a small proportion of water, of which I kept an account. When I neglected this precaution, I found that part of the acid was phlogisticated, and went off with the fixed air. Note also, that after each diffusion of acid ten minutes were allowed to the matters to unite, a precaution which I also found absolutely necessary. Hence (upon the supposition that a given quantity of fixed vegetable alkali is saturated by the same weight of both acids) we see that 11 gr. of spirit of nitre, whose specific gravity is 1.419, contain the same quantity of acid as 27 gr. of spirit of salt, salt, whose specific gravity is 1,098, that is, 3.55 gr.; the remainder of 11 gr. is therefore mere water, viz. 7.45 gr.; consequently, if the density of the acid and water had not been increased by their union, the specific gravity of the pure and mere nitrous acid should be 11,8729; for the specific gravity of this acid should be as its absolute weight divided by its loss of weight in water, and this loss should be as the total loss of these 11 gr. minus the loss of the aqueous part. Now the total loss = \(\frac{11}{1.419} = 7.749\), and the loss of the aqueous part = 7.45, and consequently the loss of the acid part is \(7.749 - 7.45 = 0.299\), and therefore the specific gravity of the acid part, that is, of the pure nitrous acid, is \(\frac{3.55}{0.296} = 11,8729\). But it is well known, that the density of the nitrous acid, as well as that of the vitriolic, is increased by its union with water; and therefore the loss above found is not the whole of its real loss in its natural state (if it could be so found), but partly the loss that arises from the density that accrues to it from its union with water: for since its density is increased by this union, its loss is less than it would be if the nitrous acid had only its own proper density, and consequently the specific gravity above found is greater than its real specific gravity. To determine, therefore, the real specific gravity of this acid in its natural state, the quantity of accrued density must be found, and subtracted from the specific gravity of the spirit of nitre, whose true mathematical specific gravity will then appear. I endeavoured to effect this by mixing different portions of spirit of nitre and water, remarking the diminution of their joint volume below the sum of the spaces occupied by their separate volumes; but could never attain a sufficient degree of precision. precision. The following method, though not exactly accurate I found more satisfactory. 12 gr. of the spirit of nitre, whose specific gravity by observation was 1,389, contained as I supposed from the former experiment 3,55 gr. of acid, and 8,45 of water; then if the specific gravity of the pure nitrous acid were 11,872, the specific gravity of this compound of acid and water should be 1,371; for the loss of 3,55 gr. acid should be 0,299, and the loss of the water 8,45; the sum of the losses 8,749. \[ \frac{12}{8,749} = 1,371; \text{ but, as I already said, the specific gravity by observation was } 1,389, \text{ therefore the accrued density in this case was at least } 0,018, \text{ the difference betwixt } 1,389 \text{ and } 1,371. \] I say at least, for as the specific gravity 11,872 was certainly too high, the loss of 3,55 gr. acid was certainly too small; and if it were greater, the mathematical specific gravity 1,371 would have been still lower. However, 0,018 is certainly a near approximation to the degree of density that accrues to 3,55 gr. acid by their union to 7,45 gr. of water, and differs inconsiderably from the truth, as will appear by the sequel: therefore subtracting this quantity from 1,419 we have nearly the mathematical specific gravity of that proportion of acid and water, namely, 1,401. And since 11 gr. of this spirit of nitre contain 3,55 gr. acid and 7,45 of water, its loss of weight should be \[ \frac{11}{1,401} = 7,855; \text{ and subtracting the loss of the aqueous part from this, the remainder } 0,405 \text{ is the loss of the } 3,55 \text{ gr. acid, and consequently the true specific gravity of the pure and mere nitrous acid is } \frac{3,55}{0,405} = 8,7654: \text{ this being settled, the mathematical specific gravity and true increase of density of the above mixtures will be found. Thus the mathematical specific gravity of } 12 \text{ gr. of that spirit of nitre, whose specific gravity by observation} \] observation was 1,389, must be 1,355, supposing it to contain 3,55 gr. acid and 8,45 of water; for the loss of 3,55 gr. acid is \(\frac{3,55}{8,763} = 0,405\), and the loss of water 8,45; the sum of these losses is 8,855. Then, \(\frac{12}{8,855} = 1,355\), and consequently the accrued density is \(1,389 - 1,355 = 0,34\). In the same manner it will be found, that the mathematical specific gravity of 13,08 gr. of that spirit of nitre, whose specific gravity by observation was 1,362, must be 1,315, and consequently its accrued density 0,047. But the whole still rests upon the supposition that each of these portions of spirit of nitre contain 3,55 gr. of acid. To verify this supposition, I could think of no better method than that of examining the mathematical specific gravities of the first mixture I had made of spirit of nitre and water in large quantities; for if the mathematical specific gravities of these agreed exactly with those of the quantities I had supposed in smaller portions of each, I could not but conclude, that the suppositions of such proportions of acid and water, as I had determined in each, was just; and that this was the case will appear by the following calculations. 1st. When to 1963,25 gr. of spirit of nitre, whose specific gravity was 1,419, 179,5 gr. of water were added, the quantity of acid upon the above supposition should be 634,53 gr.; for \(\frac{11 \cdot 3,55}{1963,25} = 634,53\). The quantity of water in those 1963,25 gr. of spirit of nitre should then be 1328,72, and after adding 179,5 gr. of water, the whole quantity of acid and water should be 2142,75, the loss of acid was \(\frac{634,53}{8,7654} = 71,24\), and the sum of the losses 1580,46: then the mathematical specific specific gravity should be $\frac{2142.75}{1580.46} = 1.355$, which is exactly the same as that which was found in 12 gr. of this spirit of nitre, on the supposition that they contained 3.55 gr. acid. Again: when to 1984.5 gr. of this mixture I added 173.75 gr. of water, the whole quantity of diluted spirit of nitre was 2163.25 gr. and the quantity of acid in 1984.5 gr. was 587.081 gr. for $\frac{12 \cdot 3.55}{1984.5 \cdot 587.081}$; the loss of this quantity of acid is 66.96 gr. and the sum of the losses of acid and water is 1643.129 gr.; and consequently the mathematical specific gravity should be $\frac{2163.75}{1643.125} = 1.315$, which is the same as that determined in 13.08 gr. of the same mixture. By continuing these mixtures until I found the mathematical specific gravity and that by observation nearly to coincide, I was enabled to draw up the following table, in which if any errors be found, I hope they will be excused, from the impossibility of avoiding them where the weights must be found with such extreme precision: the two first series were only found by analogy. | Spirit of nitre | Acid. | Water. | Accrued density. | Mathematical specific gravity. | Specific gravity by observation | Attract. of the acid to water | Attract. of water to the acid | |----------------|-------|--------|------------------|-------------------------------|---------------------------------|-------------------------------|-------------------------------| | Grs. | Grs. | Grs. | | | | | | | 9 | | | | | | | | | 10 | | | | | | | | | 11 | | | | | | | | | 12 | | | | | | | | | 13,08 | | | | | | | | | 14,15 | | | | | | | | | 15,23 | | | | | | | | | 16,305 | | | | | | | | | 17,38 | | | | | | | | | 18,445 | | | | | | | | | 19,53 | | | | | | | | | 20,605 | | | | | | | | | 21,68 | | | | | | | | | 22,755 | | | | | | | | | 23,83 | | | | | | | | | 24,905 | | | | | | | | | 26,17 | | | | | | | | | 27,34 | | | | | | | | | 28,51 | | | | | | | | | 29,68 | | | | | | | | | 30,85 | | | | | | | | | 32,02 | | | | | | | | | 33,09 | | | | | | | | | 34,26 | | | | | | | | | 35,43 | | | | | | | | | 36,60 | | | | | | | | | 37,77 | | | | | | | | | 38,94 | | | | | | | | | 40,11 | | | | | | | | | 41,28 | | | | | | | | | 42,45 | | | | | | | | The intermediate specific gravities may be found by taking an arithmetical mean between the specific gravities by observation betwixt which that sought lies, and noting how much it exceeds or falls short of such arithmetical mean; and then taking also an arithmetical mean betwixt the mathematical specific gravities. gravities betwixt which that sought for must lie, and a proportionate excess or defect. I have added a column of attraction of the nitrous acid to water as far as it keeps pace with the increase of density, but no farther, as I am unacquainted with the law of its further increase. The specific gravity of the strongest spirit of nitre yet made is, according to Mr. BAUME, 1,500; and according to Mr. BERGMAN, 1,586. I next proceeded to examine the proportion of acid, water, and fixed alkali in nitre, in the same manner as I had before done that in digestive salt, and found that 100 gr. of perfectly dry nitre contain 28,48 gr. acid, 5,2 of water, and 66,32 of fixed alkali. I shall now compare the result of these experiments with those of Mr. HOMBERG. The specific gravity of the spirit of nitre which Mr. HOMBERG made use of was 1,349; and of this, he says, 1 oz. 2 dr. and 36 gr. that is, 621 Troy, are requisite to saturate 1 French (oz. 472,5 Troy) of dry salt of tartar; according to my computation 613 gr. are sufficient; for this specific gravity lies between the tabular specific gravities by observation 1,362 and 1,337, and is nearly an arithmetical mean between them. The corresponding mathematical specific gravity lies betwixt the tabular quantities 1,315 and 1,286, and is nearly 1,300. Now, the proportion of acid and water in this is, 2,629 of acid, and \[ \frac{8,765}{7,465} \text{ of water; for } - \frac{1,300}{7,465} = 8,765 \times .300 = 2,629 \text{ of acid;} \] and the sum of both is 10,044. Now, since 10,5 gr. mild vegetable fixed alkali require 3,55 gr. of acid for their saturation, 472.5 will require 159.7; therefore, if 10,044 gr. of nitre contain 2,629 gr. acid, the quantity of this spirit of nitre requisite to give 159.7 will be 613.2 nearly, and hence the difference betwixt us is only about 8 gr. 2dly. Mr. Homberg says, he found his salt, when evaporated to dryness, to weigh 186 gr. more than before; whereas, by my experiment, it should weigh but 92.8 gr. more than at first. I shall mention the cause of this difference in treating of tartar vitriolate, for it cannot be entirely attributed to the difference of evaporation. 3dly. Mr. Homberg infers, that 1 oz. (that is, 472.5 Troy gr.) of this spirit of nitre contains 141 gr. Troy of real acid: by my computation it contains but 123.08 gr. of real acid. This difference evidently proceeds from his neglecting the quantity of water that certainly enters into the composition of nitre; for he proceeds on this analogy, \( \frac{621}{186.6} = \frac{472.5}{141} \). The proportion of fixed alkali I have assigned to nitre is fully confirmed by a very curious experiment of Mr. Fontana's, inserted in Rozier's Journal for November 1778. This ingenious philosopher decomposed 2 oz. of nitre by distilling it in a strong heat for eighteen hours. After the distillation there remained in the retort a substance purely alkaline, amounting to 10 French dr. and 12 gr. Now 2 French oz. = 944 gr. Troy, and the alkaline matter amounts to 607 gr. Troy; and, according to my computation, 944 gr. of nitre should contain 625 of alkali. So small a difference may fairly be attributed to the loss in transferring from one vessel to another, weighing, filtering, evaporating, &c. Mr. Lavoisier, in the Paris Memoirs for the year 1776, has given us, after Dr. Priestley, the analysis of the nitrous acid. In 2 oz. French measure (= 945 gr. Troy) of spirit of nitre, whose specific gravity was 1,3160, he dissolved 2 oz. and 1 dr. of mercury; the quantity of air obtained during the solution was 190 cubic inches French (= 202,55 English). This air was all nitrous. There remained a white mercurial salt, which, being distilled, afforded 12 cubic inches (= 12,785 English) of air mixed with red vapours, and which differed little from common air. There afterwards arose 224 cubic inches (= 238,56 English) of dephlogisticated air, during the production of which, the mercury was almost revivified, there remaining but a few grains of a yellow sublimate. The 12 inches of air mixed with red vapours arose, he says, from a mixture of 36 cubic inches of nitrous air (= 38,34 English) and 14 of dephlogisticated air (14,91 English); and as the mercury was almost wholly revived, he concludes, these airs arose from the nitrous acid, and formed it; and hence infers, that 16 oz. of this spirit of nitre (= 7560 gr. Troy) contained 13 oz. 7 dr. 36½ gr. (that is, 6589 gr. Troy) of water, and consequently only 971 gr. Troy of real acid, and therefore 2 oz. of this spirit of nitre contained but 120 gr. Troy of real acid: but, by my calculation, 2 oz. of this spirit of nitre contained 213 gr. acid; for its mathematical specific gravity is 1,265. The same weight of acid will also be found in it by computing the weight of the volumes of the different airs he himself found it consist of, or at least to afford by its decomposition; for 202,55 cubic inches of nitrous air weigh, by Mr. Fontana's experiment, 80,8174 gr. Troy, and 238,56 inches of dephlogisticated air weigh 100,1952 gr. Troy, and adding to these the weight of 38,34 inches of nitrous air, and of 14,91 of dephlogisticated air, which made the 12 cubic inches of air mixed with red vapours, we shall find the whole weight of these airs to be 202,181 gr.; the few grains wanting of 213 gr. may be accounted for from the absorption of the water in which he received the airs, and by allowing for that still remaining in the yellow sublimate. OF OIL OF VITRIOL. The oil of vitriol I made use of was not perfectly dephlogisticated; but though pale yet a little inclined to red. It contained some whitish matter, as I perceived by its growing milky on the affusion of pure distilled water. How far this may alter the result of the following experiments I have not tried; but believe it to be as pure as that which is commonly used in all experiments, and therefore the fittest for my purpose. To 2519.75 gr. of this oil of vitriol, whose specific gravity was 1.819, I gradually added 180 gr. of distilled water, and six hours after found its specific gravity to be 1.771. To this mixture I again added 178.75 gr. of water, and found its specific gravity, when cooled to the temperature of the atmosphere, to be 1.719; it was then milky. I then saturated the same quantity of the oil of tartar above mentioned with each of these sorts of oil of vitriol in the manner already mentioned, and found the saturation to be effected (taking the medium of five experiments) by 6.5 gr. of that whose specific gravity was 1.819; by 6.96 gr. of that whose specific gravity was 1.771; and by 7.41 of that whose specific gravity was 1.719. I was obliged to add a certain proportion of water to each of these sorts of oil of vitriol; for when they were not diluted, I perceived that part of the acid was phlogisticated, and went off with the fixed air; but knowing the quantity of water that was added, it was easy to find, by the rule of proportion, the quan- tity of each sort of oil of vitriol that was taken up by the alkali. Hence I supposed, that each of these quantities of oil of vitriol of different densities contained 3.55 gr. of acid, as they saturated the same quantity of vegetable fixed alkali as 11 gr. of spirit of nitre, which contained that quantity of acid. I then endeavoured to find the specific gravity of the pure vitriolic acid in the same manner as I before had that of the nitrous, as it cannot be had in the shape of air unless united to such a quantity of phlogiston as quite alters its properties. The loss of 6.5 gr. of oil of vitriol, whose specific gravity is 1.819 is \(\frac{6.5}{1.819} = 3.572\); but as these 6.5 gr. contained, besides 3.55 gr. acid, 2.95 of water, the loss of this must be subtracted from the entire loss, and then the remainder 0.622 is the loss of the pure acid part in that state of density to which it is reduced by its union with water. The specific gravity therefore of the pure vitriolic acid in this state of density is \(\frac{3.55}{0.622} = 5.707\). But to find its natural specific gravity we must find how much its density is increased by its union with this quantity of water; and, in order to observe this, I proceeded as before with the nitrous acid. 6.96 gr. of oil of vitriol, whose specific gravity was 1.771, contained 3.55 gr. acid, and 3.41 of water; then its specific gravity by calculation should be 1.726, for the loss of 3.55 gr. acid is \(\frac{3.55}{5.707} = 0.622\); the loss of 3.41 gr. water is 3.41; the sum of the losses 4.032. Then, \(\frac{6.96}{4.032} = 1.726\); therefore the accrued density is 1.771 - 1.726 = 0.045. Taking this therefore from 1.819, its mathematical specific gravity will be 1.774, then the loss of 6.5 gr. of oil of vitriol, whose specific gravity by observation is 1,819, will be found to be \[ \frac{6.5}{1,774} = 3.664; \] but of this 2,95 gr. are the loss of the water it contains, and the remainder 0,714 * are the losses of the mere acid part. Then, \[ \frac{3.55}{0.715} = 4.9649 \] is nearly the true specific gravity of the pure vitriolic acid. I then found the true increase of density arising from the union of the vitriolic acid and water in the foregoing mixtures, and observed, that in oil of vitriol, whose specific gravity was 1,771, it was 0,84, and in that whose specific gravity was 1,719, it was 0,100. To obtain a synthetical proof of these deductions, I compared them with the specific gravities of the first mixtures I had made; for if these deductions were true, the mathematical specific gravities, and the accrued densities, added to each other, should amount to the same quantity as the specific gravities by observation; and this I found to happen very nearly; for in the first experiment, where 2519,75 gr. of oil of vitriol, whose specific gravity was 1,819, were mixed with 180 gr. of water, that oil of vitriol contained by my calculation 1376,171 gr. of acid and 1143,597 gr. of water, besides the 180 gr. of water that were added to it, the loss of the acid was \[ \frac{1376,171}{4,964} = 277,22. \] The whole quantity of oil of vitriol was 2699,75 gr.; then the sum of the losses was 1600,81; and therefore the mathematical specific gravity \[ \frac{2699,75}{1600,81} = 1,686; \] to which, adding 0,084 the degree of accrued density, the specific gravity by observation * By mistake, the following calculations were made on the supposition that the loss was 0,715; the difference being immaterial, the calculations were not repeated. should be 1,770, which wants less than 1000th part in 2700 of being just. Again: in the mixture, whose specific gravity was 1,719 the sum of the losses was 1779,549, and the weight of the whole 2878,4, the mathematical specific gravity should be \[ \frac{2778,400}{1779,549} = 1,617, \] to which adding 0,100, the specific gravity by observation should be 1,717, which is nearly the truth. By continuing these mixtures until the specific gravities by calculation and observation nearly coincided, I formed the following table. The extra-tabular proportions are to be sought in the manner already shewn; the two first series were formed by analogy. | Acid | Water | Accrued density | Mathematical specific gravity | Specific gravity by observation | Attract. of the acid to water | Attract. of water to the acid | |------|-------|----------------|-------------------------------|---------------------------------|-----------------------------|-------------------------------| | Grs. | Grs. | Grs. | | | | | | 5.58 | | | | | | | | 6.04 | | | | | | | | 6.5 | | | | | | | | 6.96 | | | | | | | | 7.41 | | | | | | | | 7.87 | | | | | | | | 8.33 | | | | | | | | 8.79 | | | | | | | | 9.25 | | | | | | | | 9.71 | | | | | | | | 10.17| | | | | | | | 10.63| | | | | | | | 11.09| | | | | | | | 11.55| | | | | | | | 12.01| | | | | | | | 12.47| | | | | | | | 12.93| | | | | | | | 13.39| | | | | | | | 13.85| | | | | | | | 14.31| | | | | | | | 14.77| | | | | | | | 15.23| | | | | | | | 15.69| | | | | | | | 16.15| | | | | | | | 16.61| | | | | | | | 17.07| | | | | | | | 17.53| | | | | | | | 17.99| | | | | | | | 18.45| | | | | | | | 18.91| | | | | | | | 19.37| | | | | | | | 19.83| | | | | | | | 20.29| | | | | | | | 20.75| | | | | | | | 21.21| | | | | | | | 21.67| | | | | | | | 22.13| | | | | | | | 22.59| | | | | | | | 23.05| | | | | | | | 23.51| | | | | | | | 23.97| | | | | | | | 24.43| | | | | | | | 24.89| | | | | | | | 25.35| | | | | | | | 25.81| | | | | | | | 26.27| | | | | | | | 26.73| | | | | | | The specific gravity of the most concentrated oil of vitriol yet made is, according to Mr. Baume and Bergman, 2,125. I ascertained the proportion of acid water and fixed alkali in tartar vitriolate, as before, in nitre and digestive salt. I found the salts, resulting from the saturation of the same oil of tar- tar, with portions of oil of vitriol of different specific gravi- ties, to weigh, at a medium, 12,45 gr. Of this weight only 11,85 gr. were alkali and acid, the remainder therefore was water, viz. 0,6 of a grain; consequently 100 gr. of perfectly dry tartar vitriolate contain 28,51 gr. acid, 4,82 of water, and 66,67 of fixed vegetable alkali. Note, in drying this salt I used a heat of 240° to expel the adhering acid more thoroughly. I kept it in that heat a quarter of an hour. According to Mr. Homberg, 1 French oz. (or 472,5 gr. Troy) of dry salt of tartar required 297,5 gr. Troy of oil of vitriol, whose specific gravity was 1,674, to saturate it; but, by my calculation, this quantity of fixed alkali would require 325 gr.: a difference which, considering our different methods of determining the specific gravity of liquids (his method, viz. that by mensuration, giving it always less than mine) the different desiccation of our alkalies, &c. may pass for inconsiderable. The resulting salt weighed, according to Mr. Homberg, 182 gr. Troy above the original weight of the fixed alkali; but by my experiment it should weigh but 87,7 gr. more; for \( \frac{10,5}{12,45} = \frac{472,5}{560,2} \). It is hard to say how Mr. Homberg could find this great excess of weight both in nitre and tartar vitriolate, unless he meant by the original weight of the salt of tartar the weight of the mere alkaline part, distinct from the fixed air it contained: and indeed one would be tempted to think, he did make this distinction; for in that case Mr. Kirwan's Experiments, &c. on the specific Gravities case the excess of weight will be very nearly such as he determined it: for \( \frac{105}{83} = \frac{472.5}{373.3} \). Now, the whole weight of his nitre was 560.2, as I have above shewn: then \( 560.2 - 373.3 = 116.9 \), which is only 4 gr. more than he determined it. Hence he inferred, that 1 oz. (472.5 gr. Troy) of this oil of vitriol contains 291.7 gr. of acid. By my computation it contains but 213.3; but it must be considered, he made no allowance for the water contained in tartar vitriolate, and imagined the whole of the increase of weight proceeded from the acid that is united in it to the fixed alkali. Now the aqueous part in 560 gr. of tartar vitriolate amounts to 37 gr. the remaining difference may be attributed to the different degrees of desiccation, &c. OF THE ACETOUS ACID. I have made no experiment on this acid; but, by calculating from the experiment of Mr. Homberg, I find the specific gravity of the pure acetous acid, free from superfluous water, should be 2.130. It is probable, its affinity to water is not strong enough to cause any irregular increase in its density, at least that can be expressed by three decimals; and hence its proportion of acid and water may always be calculated from its specific gravity and absolute weight. 100 parts of foliated tartar, or (as it should rather be called) acetous tartar, contain well dried 32 of fixed alkali, 19 of acid, and 49 parts of water. The specific gravity of the strongest concentrated vinegar yet made is 1.069. It is harder to find the point of saturation with the vegetable than with the mineral acids; because they contain a mucilage that prevents their immediate union with alkalies, and hence they are commonly used in too great quantity. They should be used moderately hot, and sufficient time allowed them to unite. From these experiments it follows: 1st. That fixed vegetable alkalies take up an equal quantity of the three mineral acids, and probably of all pure acids; for we have seen, that 8.3 grains of pure vegetable alkali (that is, free from fixed air) take up 3.55 gr. of each of these acids, and consequently 100 parts of caustic fixed alkali would require 42.4 parts of acid to saturate them. Now, Mr. Bergman has found, that 100 parts of caustic fixed vegetable alkali take up 47 parts of the aerial acid, which, considering his alkali might contain some water, differs but little from my calculation. It should therefore seem, that alkalies have a certain determinate capacity of uniting to acids, that is, to a given weight of acids; and that this capacity is equally satiated by that given weight of any pure acid indiscriminately. This weight is about 2.35 of the weight of the vegetable alkali. 2dly. That the three mineral acids, and probably all pure acids, take up 2,253 times their own weight of pure vegetable alkali, that is, are saturated by that quantity. 3dly. That the density accruing to compound substances from the union of their component parts, and exceeding its mathematical ratio, increases from a minimum, when the quantity of one of them is very small in proportion to that of the other, to a maximum, when their quantities differ less; but that the attraction, on the contrary, of that part which is in the smallest quantity to that which is in the greater, is at its maximum. maximum when the accrued density is at its minimum, but not reciprocally; and hence the point of saturation is probably the maximum of density and the minimum of sensible attraction of one of the parts. Hence no decomposition operated by means of a substance that has a greater affinity with one part of a compound than with the other, and than these parts have to each other, can be complete, unless the minimum affinity of this third substance be greater than the maximum affinity of the parts already united. Hence few decompositions are complete without a double affinity intervenes; and hence the last portion of the separated substance adheres so obstinately to that to which it was first united, as all chemists have observed. Thus, though acids have a greater affinity to phlogiston than the earths of the different metals have to it, yet they can never totally dephlogisticate these earths but only to a certain degree; so though atmospheric air, and particularly dephlogisticated air, attracts phlogiston more strongly than the nitrous acid does; yet not even dephlogisticated air can deprive the nitrous acid totally of its phlogiston, as is evident from the red colour of the nitrous acid when nitrous air and dephlogisticated air are mixed together. Hence also mercury precipitated from its solution in any acid, even by fixed alkalies, constantly retains a portion of the acid to which it was originally united, as Mr. Bayen has shewn; so also does the earth of alum, when precipitated in the same manner from its solution; and thus several anomalous decompositions may be explained. Indeed, I have reason to doubt, whether mercury does not attract acids more strongly than alkalies attract them. 4thly. That concentrated acids are, in some measure, phlogisticated, and evaporate by union with fixed alkalies. 5thly. and attractive Powers of various saline Substances. 5thly. That, knowing the quantity of fixed alkali in oil of tartar, we may determine the quantity of real pure acid in any other acid substance that is difficultly decomposed, as the sedatif acid, and those of vegetables and animals; for 10.5 gr. of the mild alkali will always be saturated by 3.55 gr. of real acid: and reciprocally, the quantity of acid in any acid liquor being known, the quantity of real alkali in any vegetable alkaline liquor may be found. OF THE SPECIFIC GRAVITY OF FIXED AIR IN ITS FIXED STATE. Being desirous to know the specific gravity of some substances which are difficultly procured, or at least preserved for any time, free from fixed air, such as fixed and volatile alkalies, I was induced to seek the specific gravity of the former in its fixed state as of an element necessary to the calculation of the latter; it being very evident, that its density, in its fixed state, must be very different from that which it possesses in its fluid elastic state. I therefore took a piece of white marble, of the purest kind, which weighed 440.25 gr. and weighing it in water, found it to lose 162 gr.; its specific gravity was therefore 2.7175. Of this marble, reduced to a fine powder, I put 180 gr. into a phial, and expelling the fixed air by the dilute vitriolic acid and heat, I found its quantity amount to 105.28 cubic inches; the thermometer being at 65°, and the barometer between 29 and 30 inches, this bulk of air would, at 55° of Fahrenheit, occupy but 102.4 cubic inches; at which temperature, according to the experiment of Mr. Fontana, a cubic cubic inch of fixed air (the barometer being at 29°½) would weigh 0.57 of a grain; therefore the weight of the whole quantity of fixed air amounted to 58,368 gr. which is nearly one-third of the weight of the marble. At this rate, 100 gr of the marble contained 32,42 of fixed air. To determine the proportion of water and calcareous earth, and also the specific gravity of this latter, I put 300 gr 125 gr. of the same marble finely powdered into a crucible, loosely covered; the crucible and its contents, before calcination, weighed 8394 gr. and after remaining fourteen hours in a white heat I found it to weigh 7067.5 gr. The weight of the crucible alone was 5384.75 gr.; therefore the weight of the lime singly was 1682.75 gr. The marble then lost by calcination 1326.5 gr.; 180 gr. of the marble should then lose 79.343 gr. and 100 gr. should lose 44.08; but of these 44.08, 32.42 were fixed air, as is already seen, therefore the remainder, that is, 11.66 gr. were water, and the quantity of pure calcareous earth in 100 gr. of the marble was 55.92 gr. I next proceeded to discover the specific gravity of the lime. Into a brass box, which weighed 607.65 gr. and in the bottom of which a small hole was drilled, I stuffed as much as possible of the finely powdered lime, and then screwed the cover on, and weighed it both in air and water. When immersed in this latter, a considerable quantity of common air was expelled; when this ceased, I weighed it. The result of this experiment was as follows Weight of the box in air - 607.65 Its loss of weight in water - 73.75 Weight of the box and lime in air - 1043.5 Weight of the lime singly in air - 435.85 Loss of weight of the box and lime in water - 256.5 Loss of weight of the lime singly - 182.3 Hence, dividing the absolute weight of the lime by its loss in water, its specific gravity was found to be 2,390.8. From these data I deduced the specific gravity of fixed air in its fixed state; for 100 gr. of marble consist of 55.92 of earth, 32.42 of fixed air, and 11.66 of water; and the specific gravity of the marble is 2,717. Now, the specific gravity of the fixed air, in its fixed state, is as its absolute weight divided by its loss of weight in water; and its loss of weight in water is as the loss of 100 gr. of marble minus the losses of the pure calcareous earth and of the water. Loss of 100 gr. of marble = \(\frac{100}{2,717} = 36.8\) gr. Loss of 55.92 gr. calcareous earth = \(\frac{55.92}{2,390} = 23.39\) gr. Loss of 11.66 gr. water = 11.66 Then the loss of the fixed air \(36.8 - 35.05 = 1.75\); consequently, its specific gravity is \(\frac{32.42}{1.75} = 18.52\); by which it appears to be the heaviest of all acids, or even of all bodies yet known; gold and platina excepted. OF FIXED VEGETABLE ALKALI. As the manner of conducting the experiments I made on this salt was nearly the same as that I used in the foregoing (except that to find its specific gravity I weighed it in aether instead of water), I shall content myself, to avoid the repetition of tedious calculation, with relating the result of these experiments. 1st. I found that 100 gr. of this alkali contain about 6.7 gr. of earth, which, according to Mr. BERGMAN, is siliceous: this earth passes the filter with it when the alkali is not saturated with fixed air, so that it seems to be held in solution as in liquor silicum. 2dly. I found, that the quantity of fixed air in oil of tartar and dry vegetable fixed alkali is various at various times and in various parcels of the same salt; but that at a medium in the purer alkalies it may be rated at 21 gr. in 100; and hence the quantity of this alkali in any solution of it may be very nearly guessed at, by adding a known weight of a dilute acid to a given weight of such solution, and then weighing it again; for as 21 is to 100, so is the weight lost to the weight of mild alkali in such solution. The specific gravity of mild and perfectly dry four times calcined fixed alkali, free from siliceous earth, and containing 21 per cent. of fixed air, I found to be 5.0527. When it contains more fixed air, its specific gravity is probably higher, except it were not perfectly dry: from whence I inferred the specific gravity of this alkali, when caustic and free from water, to be 4.234. From the weight of the aerial acid, in its fixed state, it happens, that fixed alkalies, when united to it, are specifically heavier than when united either to the vitriolic or nitrous acids. Thus Mr. R. Watson, in the Phil. Trans. for the year 1770, p. 337. found the specific gravity of dry salt of tartar (including siliceous earth) to be 2.761: whereas the specific gravity of tartar vitriolate was only 2.636, and that of nitre 1.933. The reason why nitre is so much lighter than tartar vitriolate, is, because it contains much more water, and its union with the alkali is less intimate. Lastly, I have drawn up a table of the quantity of mild alkali, containing 6.7 per cent. of earth (which is its usual degree of purity) to be found in natural or artificial solutions of this alkali, the thermometer at 63°; and though it is not quite accurate, wanting about 1.1 per cent. of the truth, yet, I presume, it may be found useful, as this error is easily corrected. Table of the contents of a solution of mild vegetable alkali, according to its specific gravity. | Gr. of the solution | Gr. of alkali | Gr. of water | Accrued density | Mathematical specific gravity | Specific gravity by observation | |---------------------|---------------|--------------|-----------------|-------------------------------|--------------------------------| | 64.92 | | 38.67 | 0.50 | 1.445 | 1.495 | | 70.60 | | 44.35 | 0.49 | 1.393 | 1.446 | | 76.28 | | 50.03 | 0.48 | 1.356 | 1.404 | | 81.96 | | 55.71 | 0.47 | 1.324 | 1.371 | | 87.64 | | 61.39 | 0.46 | 1.297 | 1.343 | | 93.32 | | 67.07 | 0.45 | 1.274 | 1.319 | | 99.00 | | 72.75 | 0.44 | 1.254 | 1.298 | | 104.68 | | 78.43 | 0.43 | 1.237 | 1.280 | | 110.36 | | 84.11 | 0.42 | 1.223 | 1.265 | | 115.98 | | 89.79 | 0.41 | 1.209 | 1.250 | | 121.66 | | 95.4 | 0.40 | 1.198 | 1.238 | | 127.34 | | 101.15 | 0.39 | 1.187 | 1.226 | | 133.02 | | 106.83 | 0.38 | 1.178 | 1.216 | | 138.7 | | 112.51 | 0.37 | 1.170 | 1.207 | | 144.3 | | 118.19 | 0.36 | 1.162 | 1.198 | | 149.98 | | 123.87 | 0.35 | 1.155 | 1.190 | | 155.66 | | 129.55 | 0.34 | 1.149 | 1.183 | | 161.34 | | 135.23 | 0.33 | 1.143 | 1.176 | | 167.02 | 26.25 | 140.91 | 0.32 | 1.138 | 1.170 | | 172.70 | | 146.59 | 0.31 | 1.132 | 1.163 | | 178.38 | | 152.27 | 0.30 | 1.128 | 1.158 | | 184.06 | | 157.95 | 0.29 | 1.123 | 1.152 | | 189.74 | | 163.63 | 0.28 | 1.119 | 1.147 | | 195.42 | | 169.31 | 0.27 | 1.115 | 1.142 | | 201.10 | | 174.99 | 0.26 | 1.112 | 1.138 | | 206.78 | | 180.67 | 0.25 | 1.108 | 1.133 | | 212.46 | | 186.35 | 0.24 | 1.105 | 1.129 | | 218.14 | | 192.03 | 0.23 | 1.100 | 1.123 | | 223.82 | | 197.71 | 0.22 | 1.099 | 1.121 | | 229.50 | | 203.39 | 0.21 | 1.097 | 1.118 | | 235.18 | | 209.07 | 0.20 | 1.094 | 1.114 | | 240.86 | | 214.75 | 0.19 | 1.092 | 1.111 | | 246.54 | | 220.43 | 0.18 | 1.089 | 1.107 | | 252.12 | | 226.11 | 0.17 | 1.087 | 1.104 | | 257.80 | | 231.79 | 0.16 | 1.085 | 1.101 | | 263.48 | | 237.47 | 0.15 | 1.083 | 1.098 | | 269.16 | | 243.15 | 0.14 | 1.081 | 1.095 | and attractive Powers of various saline Substances. | Gr. of the solution | Gr. of alkali | Gr. of water | Accrued density | Mathematical specific gravity | Specific gravity by observation | |---------------------|---------------|--------------|----------------|-------------------------------|--------------------------------| | 274.78 | | 248.83 | ,013 | 1.079 | 1.092 | | 280.46 | | 254.51 | ,012 | 1.077 | 1.089 | | 286.14 | | 260.19 | ,011 | 1.076 | 1.087 | | 291.82 | | 265.87 | ,010 | 1.074 | 1.084 | | 297.50 | | 271.55 | ,009 | 1.070 | 1.079 | | 303.18 | | 277.23 | ,008 | 1.069 | 1.077 | | 308.86 | 26.25 | 282.91 | ,007 | 1.068 | 1.075 | | 314.54 | | 288.59 | ,006 | 1.066 | 1.072 | | 319.22 | | 294.27 | ,005 | 1.065 | 1.070 | | 324.90 | | 300.45 | ,004 | 1.064 | 1.068 | | 330.58 | | 306.13 | ,003 | 1.063 | 1.066 | | 336.26 | | 311.81 | ,002 | 1.062 | 1.064 | | 341.94 | | 317.49 | ,001 | 1.061 | 1.062 | Impure vegetable fixed alkalies such as pearl ash, pot ashes, &c. contain more fixed air, as appears by the experiments of Dr. Lewis. Pearl ash, according to Mr. Cavendish, contains 28.4 or 28.7 per cent. of fixed air. Hence in lyes of equal specific gravity with those of a purer alkali, the quantity of saline matter will be more probably in the ratio of 28.4 or 28.7 to 21; but this surplus weight is only fixed air; and hence even in these lyes the quantity of depurated salt they will afford will be found by the above table. Much also depends on their age, the oldest containing most fixed air.