114 M. Vogel on Borax and Tartar. [August, 



of lime is separated ; a quantity of this salt still, however, 

 remains dissolved in the fluid. When the fluid is evaporated, a 

 salt is obtained which weighs ■§ less than the materials employed ; 

 this partly depends upon the tartrate of lime that is precipitated, 

 and partly upon the water of crystallization in the cream of 

 tartar and borax. The soluble cream of tartar which is obtained 

 by this process is deliquescent ; it dissolves in its own weight of 

 boiling water at 54 , 5°, and in half its weight of boiling water. 

 Its solution is very imperfectly decomposed by the sulphuric, 

 nitric, and muriatic acids ; a very small proportion of the boracic 

 acid is separated, another portion is kept dissolved in the liquor, 

 but the greatest part of it remains combined with the tartar. 



M. Vogel shows in the second section of his memoir, that 

 four parts of cream of tartar and one part of boracic acid are the 

 only proportions that we can employ, in order to obtain a salt, 

 in which neither the boracic nor tartaric acids should be in 

 excess. When the soluble cream of tartar is prepared in this 

 way, it is not acted upon by boiling alcohol ; while if a larger 

 proportion of boracic acid be employed, the uncombined acid is 

 taken up by the alcohol ; and if a larger proportion of tartar be 

 used, the excess is deposited by cooling. When a very highly 

 concentrated boiling solution is poured into a cold vessel, a 

 yellow, transparent, brittle mass is formed, which is a hydrate, 

 containing "34 of water. The soluble cream of tartar calcined 

 at a red heat in a platina crucible leaves a residuum of borate of 

 lime, and borate and carbonate of potash. If boracic acid be 

 dissolved in alcohol, and the fluid be distilled, ± part of the acid 

 is volatilized, a circumstance which must be attended to in the 

 analysis of minerals. The soluble cream of tartar is considered 

 to be a chemical compound of 80 parts tartar and 20 boracic 

 acid. 



It has been doubted by chemists whether a proper combina- 

 tion can be formed between the boracic and the tartaric acids, 

 and the author is disposed to think that it can not take place. 

 The other alkaline borates, as well as borax, produce, by the 

 addition of tartar, a salt which is very soluble, very acid, and 

 deliquescent. None of the borates are deliquescent, a circum- 

 stance which proves that the solubility of the compound of cream 

 of tartar and borax is not the immediate effect of the addition of 

 a neutral borate; the union is a chemical one, and is attended 

 by the development of new properties in the substance pro- 

 duced. Alum has, in some measure, the same effect, of giving 

 solubility to cream of tartar, by being combined with it ; this 

 observation was first made by M. Berthollet, and has been more 

 fully developed by MM. Thenard and Hoard. 



The acidulous tartrate of soda was first formed by M. Ber- 

 thollet in 177b', and has been particularly attended to by M. 

 Buchoiz; it is dissolved in 12 parts of cold water ; by the union 

 of boracic acid and the borates, the salt becomes very acid, and 



