AMIDOSULPHOXiO ACID. 231 



nearly saturated with .sodium hydrogen sulphate, it yields some of its 

 acid on standing, after admixture with sulphuric acid. Nitric acid 

 also precipitates amidosul phonic acid from its solution, but to a much 

 less extent than sulphuric acid. A fuming solution of hydrochloric 

 acid does not precipitate it. Glacial acetic acid acts well as a 

 precipitant, but more of it must be used than of sulphuric acid. It is 

 stable in the air (even when crude) and non-deliquescent in the cold, but 

 it generally holds about one per cent, of water, either hygroscopically 

 or to a slight extent as ammonium acid sulphate. It is also stable in 

 cold solution (Berglund), or very nearly so. Dilute hydrochloric 

 acid and barium chloride along with it do not seem to lessen its 

 stability in the cold. A solution of the acid may be boiled for a 

 moment or be kept at 100° for a very few minutes, and still fail to 

 show sulphuric acid with barium chloride. At 45° there is just enough 

 hydrolysis in 2 hours to give a turbidity with barium chloride in 20 

 seconds. The presence of hydrochloric acid in a boiling solution quickens 

 the destruction of the acid very much, but does not quite complete it in 

 tlie course of a few hours. Heating to 150° makes the hydrolysis com- 

 plete in presence of hydrochloric acid, in three or four hours (Raschig). 

 Berglund stated that the acid in aqueous solution can be boiled for 

 an hour without decomposition occurring, though continued boiling 

 decomposes it ; and that, though hydrochloric acid hastens matters, 

 the solution may be boiled with this acid and barium chloride 

 for an hour, before barium sulphate begins to separate. Also 

 Raschig stated that in its boiling solution, the acid is practically 

 undecomposed, and only very slowly decomposed in presence of 

 acids. 



According to our experience, just recorded, Berglund and Raschig 

 have magnified the degree of stability of the acid in boiling solutions. 

 Ivrafft and Bourgeois, on the other hand, magnified still more its 



