360 On the Alteration which Sulphuric Acid 



moment when it is safficiently concentrated to crystallize, there 

 is obtained by the refrigeiiUion the pfoto-sulphovinate of lime. 



This salt is in small flakes; it has a peculiar burnt taste; it 

 attracts humidity, and inflames when a lighted candle is applied 

 to it. Strongly heated it becomes black and very acid. The de- 

 composition which is announced by this black colour, takes place 

 as soon as, by the progress of the evaporatio;), salt is deposited on 

 the sides of the vessel ; it extends even to the whole of the salt, 

 if at the moment when it begins to manifest itself it is not stopped 

 bv the addition of a little chalk ; and the liquor, in which no 

 trace of sulphuric acid could previously be discovered, contains 

 then a great excess of it. The acid of proto-siilpliovinate of lime 

 or of barytes may be easily obtained by decomposing tlie liquor by 

 sulphuric acid. This new acid gives the vvhole secret of etheri- 

 fication, since it is produced with sulphuric ether. Many che- 

 mists believe that the sulphuric acid loses none of its saturating 

 property in acting upon alcohol; but the reverse is the case, as 

 any person may convince himself by testing the acid before and 

 after its action on alcohol. 



Almost all the organic substances and powerful acids act in 

 the same manner. 



The second acid {deui-uenot hionicum) is found in the residue . 

 of the distillation of the ether, treated several times with alco- 

 hol and perfectly exhausted, but fresh, and not black or altered. 

 This residue is saturated with chalk or with carbonate of barytes, as 

 already mentioned. The deuto-sulphovinate of lime is very sweet, 

 and possesses the property of absorb ng the oxygen from the air, 

 and of producing sulphate of lime, a good deal of sulphuric acid, 

 and the third acid {Ir it -cenot hionicum). It is thus seen why the 

 residue of the preparation of ether restored to the air the pro- 

 perty whicli it had lost of giving ether; and why it saturates 

 then more than before. The sulphovinous deut-acid produces 

 thus by decomposition much sulphuric acid and the sulphovinous 

 trit-acid. 



The sulphovinous trit-acid is obtained very easily by exposing 

 to the air, until there is no longer any absorption of oxygen, 

 either the second acid or the exhausted residue of the distilla- 

 tion of sulphuric ether. By saturating with chalk the trito-sul- 

 phovinate of lime is obtained, which is deliquescent when exposed 

 to the air, and, like all acetates, combustible. It has very nearly 

 the same savour as the first sulphovinate of lime, and has many 

 affinities with this salt. 



The sulphovinous acids are easily isolated from their combina- 

 tions with lime or with l)arytes. Distilled, each of them gives a dif- 

 ferent product. The three sulphovinates of lime give,for example, 

 by distillation, three new liquid crystalHzable afcids remotely re- 

 sembling 



