l68 PHILOSOPHICAL TKANSACTIONS. [AN.VO 1782. 



//. New Chemical Experiments relative to the Acid extracted from Fat. By 

 Dr. Crell. An Abstract from the Latin, p. 8.* 



To obviate the objection that in the mode of obtaining the concentrated acid 

 of fat by the action of the vitriolic acid on Segner's salt, some of the vitriolic 

 acid might be volatilized with it; Dr C. 



Exper. 56, put 3 oz. of Segner's salt (i. e. of the salt compounded of the 

 vegetable alkali and the acid of fat) into a coated glass retort, and subjected the 

 same to the open fire, gradually increased. A small quantity of water first came 

 over, viz. the water of crystallization. When the heat was increased to such a 

 degree that the retort began to be red-hot, there immediately rose up an abun- 

 dance of grey vapour, indicative, as Dr. C. thought, of a strong acid; but on 

 opening the vessels, after they had become cold, he perceived no fumes nor any 

 of the smell peculiar to the acid; but rather the smell of spirit of tartar, with 

 which the obtained fluid, weighing 11 dr., agreed in other respects, viz. in taste 

 and colour; it effervesced slightly with salt of tartar. The residuum was an al- 

 kaline salt, with an admixture of carbonaceous matter, but without any trace of 

 volatile alkali. 



The method of obtaining the smoking acid of fat, acidum pinguedinis fumans, 

 had been hitherto extremely tedious, 9 distillations, exper. I-9, being required, 

 besides rectification, exper. 46; after which the acid was to be saturated with an 

 alkali, the solution to be evaporated, the salt thus obtained to be calcined, and 

 then again to be dissolved and the solution to be evaporated, before the oil of 

 vitriol could expel a pure acid from it, exper. 53. He was therefore anxious to 

 obtain a pure acid of fat by a shorter process. Accordingly 



Exper. 57, he distilled some purified suet in copper vessels lined with tin. 

 On applying a gentle heat nothing rose up but water; but when the heat was in- 

 creased, there followed a greenish fluid. At the same time the tin in various 

 parts of the alembic, and especially in the tube adapted to it, was melted, and 

 had penetrated to the outside. When the distillation was over, he found in the 

 receiver the acid and oil, not as in the former experiments congealed, but in a 

 fluid state, though the residuum was almost wholly converted into a coally matter. 

 Thus he had discovered a shorter process; not only however was the acid conta- 

 minated with copper, but the vessels were so much damaged by the great degree 

 of heat to which they had been subjected, that they would hardly serve for any 

 other operations afterwards. 



Abandoning therefore this method, which was not attended with the desired 

 success, he thought of having recourse to a solution of suet in an alkaline salt, 

 j. e. to soap. For it appeared to him highly probable, that the alkaline salt, at 



* See vol. xiv. p. 666, of these Abridgments. 



