20S Miscellaneous Intelligence. 



and which he has practised for some years. The proportions of 

 the materials are — 



Blood, considered as in the dry state, 3 parts 

 . Nitre 4 •<« U o'^u^h^i^i^ 'y , 1 part 



Iron scales , ' . * : tV of the blood employed. 



The blood is first to be coagulated in a large copper cauldron, and 

 the serum being separated by means of a press, the coagulum is 

 to be returned to the cauldron with the nitre and iron. The quan- 

 tity of water contained in the blood is sufficient to liquify the salt, 

 so as to allow of an uniform mixture being etfected. The mixture 

 is then removed, and exposed in an airy situation to dry, the putre- 

 faction of the blood being prevented by the nitre. When the de- 

 siccation is complete, the mixture is charged into cast iron cylin- 

 ders, which are fixed in a reverberatory furnace, and in all things 

 resemble those used in the preparation of animal charcoal. These 

 are to be raised to a brown red heat, until no more vapour is dis- 

 engaged, and then left until nearly cold, after which the contents 

 are to be withdrawn and put into a wooden vat, with twelve or fif- 

 teen times their weight of water, for an hour. The fluid is then 

 to be filtered through a cloth, and evaporated until of 32° of Beaue 

 (specific gravity 1.284.) Being then left to cool, a large quantity 

 of well-crystallized bi-carbonate of potash is obtained. M. Gautier 

 Says he has not, as yet, been able to explain how it is that this 

 bi-carbonate has been formed at so high a temperature ; a portion 

 also appears to be decomposed during the evaporation of the solu- 

 tion, which, at first but slightly alkaline, becomes sensibly so by a 

 prolonged evaporation. 



As the same product is not obtained when potash is used in place 

 of nitre, it is probable that the elements of the nitric acid perform 

 a particular part in the operation. 



The solution which has given the crystals of carbonate of potash 

 contains a little carbonate of potash, and much ferro-prussiate of 

 potash. It is to be concentrated to 34° (specific gravity 1.306), and 

 placed in wooden vessels lined with lead. In the course of some 

 days a greenish crystalline mass is obtained, which being redis- 

 solved in a fresh quantity of pure water, and evaporated to 32*^ or 

 33° (specific gravity 1.295), is to be recrystallized. 



Sometimes, when using potash, M. Gautier has mixed nitre with 

 it, and has always obtained a richer product than when potash alone 

 had been employed. — Jour, de Phar. 1827, p. 11. 



19. Sulphocyanide of Potassium in Saliva. — MM. Tiedemann 

 and Gmelin have observed the existence of this peculiar compound 

 in saliva, in two cases ; the one when the fluid was secreted during 

 smoking, and the other when no such stimulus was ^ppHed. — Ann. 

 de Cliimie, xxxv. 266. 



20. Decomposition of Sulphate of Copper by Tartaric Acid.-^ 



