vii OXIDATION-PRODUCTS 241 



AgN0 3 precipitate is freed from silver with H 2 S, the latter removed 

 by a current of air ; the solution is then neutralised with NaOH and 

 precipitated with mercuric acetate. By decomposing the mercury 

 precipitate with H 9 S there is obtained the ' Peroxyproteic acid B.' 



The nitrate remaining from the first lead precipitate was then 

 precipitated with mercury acetate. On decomposing the voluminous 

 precipitate with H 9 S, there was obtained ' Peroxyproteic acid C.' 



All peroxyacids are readily soluble in water, slightly soluble in 

 dilute alcohol, insoluble in acetone and ether. The watery solution 

 gives an intense biuret reaction, but no xantho-proteic reaction, nor 

 the tests of Millon or Hopkins or the lead-sulphide reaction. 



Phospho-tungstic acid in the presence of a trace of HC1 gives a 

 voluminous precipitate ; if too much HC1 is present no precipitate is 

 formed, and if no HC1 is present the precipitate first formed dissolves 

 in an excess of the phospho-tungstic acid. Phosphomolybdic acid 

 precipitates to a lesser degree, and the other alkaloidal reagents do not 

 precipitate at all. Mercuric acetate and nitrate give a voluminous 

 precipitate insoluble on heating and in acetic acid, but readily soluble 

 in HC1. Mercuric chloride does not precipitate. Silver nitrate added 

 to the free acid causes no precipitate, but on adding baryta water, 

 drop by drop, a white precipitate, soluble in acetic acid and ammonia, 

 is formed. A neutral salt of a peroxyproteic acid is precipitated directly 

 with AgNO 3 . Lead acetate causes a precipitate soluble on warming 

 and in acetic acid. When heated with copper-acetate green flocculi 

 are separated out, which are soluble in NH 3 , with a deep blue, and in 

 NOH with a biuret-colour. Ferric chloride gives a gelatinous pre- 

 cipitate insoluble in acetic acid, but readily soluble in HC1. Zinc- and 

 tin-chlorides do not precipitate. 



With calcium and barium carbonate, magnesium and zinc oxides, 

 or by neutralisation with sodium carbonate and ammonia readily 

 soluble, non-cry stallisable salts are formed. No insoluble compounds 

 were obtained with benzoyl- chloride, benzoyl-sulpho- chloride, and 

 miphthol-sulpho-chloride and alkali. 



The peroxyproteic acids B and C differ from A in their behaviour 

 towards neutral and basic-lead acetate and silver nitrate, as C is not 

 precipitated by either of these, while B is precipitated by lead-acetate 

 but not by neutral lead-acetate and AgN0 3 . 



Peroxyproteic acid esters were obtained by boiling the dry peroxy- 

 proteic acids with alcoholic HC1 (1 part of alcohol saturated with 

 gaseous HC1 to 10 parts of absolute alcohol) for one to two hours in a 

 reflux boiler. The alcohol was removed by distillation in a vacuum 

 under 30-40 mm. pressure, and the syrup-like residue kneaded with 



R 



