Elements of the Theory and Practice of Chymistry, 5th ed.

by Pierre Joseph Macquer

Those Chymists who looked upon the Salt of Amber as a Volatile Alkali, either did not examine it thoroughly, but contented themselves with its first appearance, in which it resembles the Volatile Salt of animals, or else were led into the error by some particular circumstances. We know, for example, that animal as well as vegetable substances are dug out of the earth. The insects, sometimes found inclosed in lumps of Amber, sufficiently prove this. Perhaps they made their experiments on such pieces of Amber; or else, that which they used might be mixed with some animal substance not very perceptible. In such a case, it would be no wonder if the Volatile Salt obtained should shew some tokens of an Alkali: for the Volatile Alkali arising from the animal matter would only be mixed, not combined, with the Salt of the Amber; as the great quantity of the Oil, in which both these Salts are entangled, would hinder them from dissolving each other, and forming such a Neutral Salt as would be produced in other circumstances.

The acid or alkaline nature of the Salt of Amber was not the only point that remained to be discussed on this occasion. Its acid quality being once clearly ascertained, the nature of this Acid was next to be determined. This is the object chiefly aimed at in Mr. Bourdelin's Memoirs, and his discovery thereof is unquestionably one of the finest, and at the same time one of the most difficult, that could be attempted with regard to this Bitumen.

It appears plainly from several experiments, of which we have given an account in the course of this work, that the strongest mineral Acids, by being combined with an oily matter, are so vastly altered, and so strangely disguised, that we not only are incapable of distinguishing what they are, but even can hardly avoid decomposing, and partly destroying them, by those very operations which seem the best adapted to separate them from the Oil in which they are inviscated. Mr. Bourdelin had all these difficulties to surmount, and incessantly met with new obstacles in that troublesome fatty matter, which, like an impenetrable veil, concealed from his view the Acid whose nature he wanted to discover. But at last, by dint of manifold experiments, he happily gained his end. Two parts of pure Nitre, unadulterated with the lead particle of Sea-salt, and one part of Amber, pulverized and mingled together, procured him, by deflagration, a Salt partly neutral and partly alkaline; which being lixiviated, and set to evaporate spontaneously, there formed at the bottom a residue of a mucilaginous, pappy, whitish matter, amongst which he could distinguish crystals, that were very transparent, regularly figured, of a cubical form, but rather oblong; so that they represented little oblong squares most exactly formed, and about half a line thick.

As these crystals perfectly resembled, in their figure, the Neutral Salt produced by a combination of the Acid of Sea-salt with the alkaline basis of Nitre; this was a proof to Mr. Bourdelin that the Acid of Amber is of the same kind, or rather exactly the same, with that of Sea-salt. The Nitre being alkalizated by means of the phlogiston of the Amber, the Acid of the Bitumen, finding this Alkali a proper basis to fix in, unites with it, and by that means is enabled to resist the action of the fire, so as not to be carried off by it.

On the other hand, it is separated from the fat matter by which it was masked before; for by the help of this fat matter the Nitre is alkalizated. The Acid, having by this means recovered all its properties, begins to discover them, as hath been said, by the figure it constantly gives to the crystals of the Neutral Salt which it helps to constitute.

Moreover, this Neutral Salt hath all the essential properties of Sea-salt. It hath its taste; it decrepitates in the same manner on live coals; if Oil of Vitriol be poured on it, white vapours arise, which have the smell of Spirit of Salt, and are an actual Spirit of Salt. Lastly, it makes a white precipitate of Mercury dissolved in Spirit of Nitre, and a luna cornea of Silver dissolved in the same Spirit; which last proofs would alone be sufficient to establish Mr. Bourdelin's opinion, though we had no other.

It were to be wished that the experiments which Mr. Bourdelin hath made on Amber were also tried on other Bitumens. There is reason to think they would be found to contain either the Marine or the Vitriolic Acid: for though they do not yield a Volatile Salt, as Amber doth, in distillation, yet the Acids obtained from them are very strong, and appear, as we said before, to have a mineral origin. Mr. Geoffroy observed, that Amber, being pulverized and infused in hot water, parts with its Salt in the same manner as Benjamin does; which gives room to suspect that Amber is to Bitumens what Benjamin is to Resins.

PROCESS IV.

The Analysis of Bees-Wax, and such Oily Compounds as are analogous to it.

Melt the Wax you intend to analyze, and mix with it as much fine sand as will make it into stiff paste. Put this paste in little bits into a retort, and distil as usual, with a graduated fire, beginning with a very gentle heat. An acid phlegm will come over, and be followed by a liquor which at first will look like an Oil, but will soon congeal in the receiver, and have the appearance of a butter or grease. Continue the distillation, increasing the fire by insensible degrees, till nothing more will come off. Then separate the butter from the acid phlegm in the receiver, mix it with fresh sand, and distil it again just as you did the Wax before. Some acid phlegm will still come off, and an Oil will ascend, which will not fix in the receiver, though it be still thick. Continue the distillation, with a fire so governed that the drops may succeed each other at the distance of six or seven seconds of time. Do not increase it, till you perceive the drops fall more slowly; and then increase it no more than is necessary to make the drops follow each other as above directed. When the distillation is finished, you will find in the receiver the Oil come wholly over, and a little acid phlegm. Separate the Oil from this liquor; and, if you desire to have it more fluid, re-distil it a third time in the same manner.