GLYCERINE. 241 



Glycerine cannot be regarded as a hydrate of oxide of lipyl, 

 because in its combinations it always contains 3 atoms of water 

 more than a double atom of oxide of lipyl ; and we know that no 

 haloid base retains its hydrate-water when it combines with 

 acids. 



Combinations. No neutral salts of glycerine have yet been 

 exhibited, but we are acquainted with several of its acid salts, 

 which, like the acid salts of the oxides of ethyl and methyl, unite 

 with bases, and form a series of compounds. 



Bisulphate of glycerine (glycero-sulphuric acid] C 6 H 7 O 5 .SO 3 + 

 HO.SO 3 , is formed by the direct union of glycerine with sulphuric 

 acid ; the excess of sulphuric acid is removed by saturating with 

 carbonate of lime or baryta ; the sulphate of glycerine-lime or gly- 

 cerine-baryta is decomposed with oxalic acid and the filtered fluid 

 evaporated in vacuo. 



This acid salt forms a colourless fluid, which, on evaporation 

 even in vacuo, is readily decomposed into glycerine and sulphuric 

 acid; it has a strongly acid taste, reddens litmus, and forms easily 

 soluble double salts, even with baryta and lime. These salts readily 

 yield glycerine when boiled, and even more readily when treated 

 with an excess of base ; the dry salts when heated carbonise and 

 develope a vapour (containing acrolein) with an extremely disagree- 

 able odour, and irritating to the eyes. The lime-salt crystallises in 

 colourless needles, and=CaO.SO 3 + C 6 H 7 O 5 .SO 3 . 



Acid phosphate of glycerine , (glycero-phosphoric acid,) 

 C 6 H 7 O 5 .2HO + PO 5 , is obtained by the direct action of syrupy 

 glycerine on pulverised glacial phosphoric acid, which developes 

 much heat, the temperature even rising to 100. The excess of 

 phosphoric acid is removed by baryta, and the baryta-salt decom- 

 posed by sulphuric acid. When in a concentrated state the body 

 in question forms a colourless fluid, which even in vacuo cannot 

 be very strongly concentrated without undergoing decomposition ; 

 it does not crystallise, has a strongly acid taste, and dissolves 

 freely in water and alcohol; with bases it forms double salts, 

 which dissolve readily in water, but so very slightly in alcohol that 

 this fluid precipitates them from their aqueous solutions. Phosphate 

 of glycerine-lime, 2CaO + C 6 H 7 O + PO 5 , crystallises in white, glis- 

 tening scales, and dissolves in cold water ; it is, however, so slightly 

 soluble in hot water that it is precipitated from its aqueous solution 

 by boiling. The baryta-salt contains I atom of tribasic phosphoric 

 acid, 2 atoms of baryta, and 1 atom of glycerine. 



Bitartrate of glycerine, C 6 H 7 O 5 .C 4 H 2 O 5 +HO.C 4 H 2 O 5 , is pro- 



