NON-EXISTENCE OF AMIDOSELENITES. 211 



In just such ways as the more acid ammonium selenite 

 can be prepared from the normal or the less acid selenite, did 

 Cameron and Macallan get the acid selenosamate from the 

 normal selenosamate. No property of the selenosamates is re- 

 corded by which they are distinguishable from the acid selenites. 

 It is indeed stated that a neutral solution gives hardly any 

 precipitate with barium chloride until ammonia is added, but 

 then that is equally true of a neutral solution of ammonium 

 selenite, the normal salt being strongly alkaline. 



The only difficulty, but it is a great one, in the way of 

 regarding the selenosamates as being merely selenites lies in the 

 fact that the quantities of ammonia found in the two salts are 

 just those proper to the selenosamates and not in the least those 

 proper to the selenites. This difficulty, we believe, may be 

 legitimately surmounted, until further evidence is forthcoming, 

 by calling in question the propriety of the methods of analysis 

 by which such results were reached. In the first place, the 

 normal selenosamate, described as continuously losing ammonia, 

 was dried for analysis in a partial vacuum over sulphuric acid, 

 and yet gave the right proportions of both selenion dioxide and 

 ammonia very closely indeed. Secondly, the selenion dioxide 

 was estimated by passing chlorine into the solution of the 

 selenosamate and then precipitating barium selenate ; it was 

 therefore estimated by a method which H. Eose in 1861 {Fogg. 

 Ann. 113, 472 ; Z. anal. Ch., 1, 75) had condemned as being 

 quite unsatisfactory and utterly unreliable for reasons given, 

 and which has again been discredited by Boutzoureano {Ann. 

 Chim. Fhys.y 1889 [6] 18, 296) as being far from giving good 

 results. Lastly, they record no attempt to estimate the ammonia 

 by direct distillation with alkali and give no reason for not 



