CHAP. I.
In which is shewed, the Compleat or Utmost Impregnation of WATER with several kinds of Salt, both together, and apart.
N discourse upon a Lecture formerly read, concerning the Lixivial Salts of Plants; It was mentioned, as a thing asserted by some Phylosophers, That Water having been fully impregnated with one kind of Salt, so as to bear no more of that kind; it would yet bear, or dissolve some portion of another; and so of a third. And it was referred to Me by this Honourable Chair, to examine and produce the Experiment. The doing whereof brought into my mind divers other Experiments hereunto relating.
2. §. As next, With what difference of quantity this Superimpregnation would be made, upon the Solution of different Salts?
3. §. Thirdly, Whether the Solution of a smaller quantity of several Salts, doth consist with the non-increase of the bulk of the Water? Because this also is affirmed by some.
4. §. Fourthly, What quantity of the several kinds of Salt, may be dissolved severally, in the same quantity of Water?
5. §. Fifthly, Whether by dissolving a Salt in Water, there be any Space gained, or not? That is, whether the Bulk of the Water be greater, before the Salt lying in it be fully dissolved, than it is afterwards? Or if a Cubick Inch of Salt be dissolved in nine Cubick Inches of Water; Whether the Water will then fill a Vessel of ten Cubick Inches content?
6. §. Sixthly, Whether the Space be equally gained, by an equal encrease of the same Salt?
7. §. Seventhly, Whether upon the Solution of several kinds of Salts, be gained so many several quantities of Space? That is, if the Solution of common Salt gains, suppose, an Inch, whether the Solution of Salt Armoniack gains as much, or more, or less? and so for other Salts.
8. §. Eighthly, What that just space may be, which any Salt gaineth with respect to its own Bulk, or that of the Water?
9. §. And first, for the Superimpregnation of Water; I put into a bottle ℥ij of fair Water; adding thereto, first half an Ounce of Nitre; and afterwards more, as the Water would dissolve it; and (that I might be sure the Impregnation was full) some portion above what the Water would bear. Then having separated this remaining portion; I put to this Solution of Nitre, two Drachms of Sal Armoniac; which wholly and easily dissolved in the said Solution; though it would not bear a grain more of Nitre. I then added a third Drachm of Sal Armoniac, after that a fourth, and a fifth; all which, within the space of half an hour, were perfectly dissolved in the said Solution, without any precipitation of the Nitre.
10. §. In the making of this Experiment, two things, to render it infallacious, are to be noted. That the said Salts were not dissolved by the help of Fire, but only by a strong and continued Agitation. And that this was done upon a warm day: which I mention, because that even the changes of the weather will somewhat alter the Solubility of the Salts.
11. §. Having made the Experiment upon two Salts, I proceeded to repeat it upon three. And first I dissolved as much common Salt in ℥ij of Water, as that quantity would bear. Then having separated the subsiding portion; I put to the Solution, no less than five Drachms of Nitre, which by a continued Agitation, was wholly dissolved therein, neither the Nitre nor the common Salt being in the least precipitated. Then adding a Scruple more, it would not dissolve, but subsided. This second subsiding portion, I again separated; and then put to this Superimpregnation, near ʒj of Sal Armoniac, which was also dissolved as the former. And if as many more Salts had been added, ’tis probable that the same Water would have born some quantity of them all.
12. §. From this Experiment, it is a Conclusion demonstrated, That not only the visible Crystals, but the very Atomes of every Salt, at least those Particles which are ultimately dissolved in Water, have a different Figure one from another. Because that if they were all of one Figure; there would be no Superimpregnation, but the Pores of the same Water, would imbibe as much of one Salt, as answers to the total of two more Salts imbibed: that is to say, it would as well imbibe two Ounces of common Salt, as one Ounce of common Salt and another of Nitre: which yet is contrary to the Experiment. And it is the same thing, whether we suppose the Pores of Water to be also different, or not. Because, that if the Figure of all the said Atomes be the same; then their respect to the Pores of the Water must be the same, how different so ever those Pores be: which is also contrary to the Experiment. Besides it is a great presumption, to say, that the Pores, and therefore the Atomes of Water have different Figures; and yet not those of Salts.
13. §. From the same Experiment we may go upon good ground in Compounded Infusions; whether of Purgative, or other Materials. As not doubting, but that the same Menstruum may be highly impregnated with several Ingredients at once, whose operative parts may be therein copiously dissolved, without hindring either an Extraction, or causing a Precipitation one of an other.
14. §. The Second Enquiry is, With what difference this Superimpregnation of Water is made? which I find considerable. For a Solution of above five Drachms of Nitre may be superimpregnated with no less quantity of Sal Armoniac. And a Solution of five Drachms of common Salt, may be superimpregnated with as much Nitre. Yet neither a strong Solution (as of five Drachms) of common Salt, will bear above two Scruples of Sal Armoniac: nor will a strong Solution (as of five Drachms) of Sal Armoniac, bear above a Drachm of common Salt: for if above the said quantities of either of them be mixed together: they are both copiously and forthwith precipitated to the bottome of the Glass.
15. §. Whence, notwithstanding the former Experiment, yet are we admonished, not to infuse all manner of Ingredients in any proportion. Because though some do not, yet others will precipitate one another.
16. §. The Third Enquiry was this, Whether the Solution of a smaller quantity of several Salts, doth consist with the non-increase of the Bulk of the Water? For this I took a Bolthead with a slender Neck, conteining about a pint and a quarter of Water; and dissolved therein about ℥jß of Nitre. And marking the place to which the Water ascended in the Neck of the Bolthead: I then dissolved in the same Water about a Drachm of Sal Gemmæ: which little quantity, raised the Water above half an Inch higher then it was before. The like I observed in the addition of Nitre to a Solution of Sal Armoniac. So that to suppose the variation of the Salt doth prevent the increase of the Bulk of the Water, is a manifest Error.
17. §. From the same Experiment it also appears, That the ascent of the Water upon a Superimpregnation, is the same, by whatsoever Salt the first Impregnation be made. For instance, Let a Solution of Nitre ascend in the Neck of the Bolthead, suppose, to 10 Inches, then add ½ an Ounce more of Nitre, so as to raise the Water, suppose, 12 Inches or more, or less, according to the Bore of the Neck. In like manner, let a Solution of Sal Armoniac reach to ten Inches: then add again half an Ounce of Nitre; and it will reach just 12 Inches, or more or less, as before.
18. §. The Fourth Enquiry is, What quantity of the several kinds of Salt, may be dissolved severally in the same quantity of Water: that is to say, by agitation alone, without the help of fire, as I noted before. And upon tryal it appears, First, that two Ounces of Water will dissolve three Ounces of Loaf-Sugar and no more, except the Water be heated.
19. §. The same quantity of Water that is, two Ounces will dissolve above two Ounces of Salt of Tartar. I say above, for how much more, want of a greater quantity of Salt which I could confide in, made me that I could not finish the Experiment.
20. §. The same quantity, sc. two Ounces of Water, dissolveth an Ounce and a Drachm of Green Vitriol.
21. §. The like quantity dissolveth six Drachms and a Scruple or above ¾ of an Ounce of common Salt.
22. §. Of Nitre, Five Drachms two Scruples and an half.
23. §. Of Sal Armoniac, five Drachms and two Scruples.
24. §. Of Alum, not above two Drachms and a Scruple.
25. §. And of Borax, not above a Drachm and half a Scruple.
26. §. Of these note, That although Common Salt be very dissoluble, and will presently catch the moysture of the Aer: yet a much greater quantity not only of Salt of Tartar, but even of Loaf Sugar, and of Green Vitriol it self, may be dissolved in Water than of Common Salt.
27. §. Again, as the great Solubility of some, so the less Solubility of other Salts is also observable, as of Alum, and Borax. For the same quantity of Water will dissolve near four times as much of Green Vitriol, as it will of Alum. And of Sugar more than ten times as much. Of Green Vitriol near eight times as much as of Borax; and of Sugar, twenty times as much.
28. §. From this Experiment we are likewise cautioned, not only in the Infusion of several Ingredients together, but of any one singly; that such a proportion thereof to the Menstruum, be not exceeded. For all that is over and above what the Menstruum will bear, is either not extracted, or will be precipitated. As is evident not only in the Dissolution of the Salts above named, but in the Infusion of Plants themselves: as, for instance, of Senna; two Drachms whereof will impregnate four Ounces of Water as strongly, as if twice the quantity were infused; because the Water will bear no more of the Purgative Parts of that Body.
29. §. There is only one Salt more remaineth to be spoken of under this Experiment; and that is, the Crystals of Tartar. Whereof, it is somewhat strange to observe, that it will scarce at all dissolve in Water: not more, than even divers Resinous Gums, as Mastick, Tolu, Tacchamahacca, and some others will do. For if two Drachms, suppose of these Crystals, of Tartar (commonly sold for Cremor Tartari) be put to one Ounce of Water, scarce five Grains thereof will, by Agitation, be therein dissolved.