ON MILK 201 



spirit of wine by distillation, the acid of milk remained in 



the retort, as pure as in my opinion it ever can be got by a 

 chemical process. 



SECTION IX. 



The nature of this acid, and its effects upon earths, 

 alkalies, and metals, I found to be as follows : (1) Evaporated 

 to the consistence of a syrup, it yields no crystals ; and when 

 evaporated to dryness it deliquesces again. (2) When dis- 

 tilled, water first comes over, then a weak acid, like spirit of 

 tartar ; afterwards, some empyreumatic oil, with more of the 

 same acid, aerial acid, and inflammable air; in the retort 

 there remained a coal. (3) Saturated with fixed vegetable 

 alkali, it yields a deliquescent salt, soluble in spirit of wine. 

 (4) A salt of the same kind is obtained with fixed mineral 

 alkali, which does not crystallise, but dissolves in spirit of 

 wine. (5) Combined with volatile alkali, it produces a kind 

 of sal ammoniac, which, however, deliquesces, and, when 

 distilled, yields a great deal of its volatile alkali before the 

 acid is destroyed by the heat. (6) Combined with terra 

 ponderosa, lime and clay, it forms deliquescent neutral salts ; 

 but with magnesia it yields small crystals, which, however, at 

 last are again deliquescent. (7) This acid of milk has no 

 effect either in a digesting or a boiling heat on bismuth, 

 cobalt, regulus of antimony, tin, quicksilver, silver and gold. 

 This acid, however, having been digested with tin, precipitated 

 the gold from its solution in aqua regia, in the form of a 

 black powder. (8) It dissolves iron and zinc, and produces 

 inflammable air. The solution of iron was brown, and 

 yielded no crystals ; but the solution of zinc crystallised. 

 (9) Copper communicated to this acid first a blue, then a 

 green, and at last a dark blue colour, without crystallising. 



