44 • JOURNAL OF THE 



determined as pointing suflBciently accurately to the nature of the 

 body formed. Corrections were made for the percentage of water 

 retained in the powders analyzed. Generally two simultaneous lead 

 determinations were made of each substance. The means of con- 

 cordant analyses are given : 



1. Substance heated on water-bath gave 62.50 p. c. Pb. 



2. Substance heated on sand-bath gave 60.11 p. c. Pb. 



3. Substance standing in the cold ga,ve 58.82 p. c. Pb. 



Calculated for Pbl^. PbO p. c. Pb = 6o.5i. Calculated for Pblg. 2PbO 



p. c. Pb. =68.45. 



From this it would seem that the ammonia which was only mod- 

 erately heated had the greatest effect ; that which was not heated 

 at all had the least. 



In the second set of experiments the heating lasted only seven 

 hours (the mixture stood three days before heating) but care was 

 taken to insure a strong solution of ammonia covering always the 

 iodide. The results were as follows : 



1 . Substance heated on water-bath gave 64. 1 3 p. c. Pb. 



2. Substance heated on sand-bath gave 63.25 



k( 



Another set heated ten hours without previous standing were 

 analyzed : 



1. Substance heated on water-bath gave 61.60 p. c. Pb. 



2. Substance heated on sand-bath gave 60.37 



(( 



From these results it is seen that the longer ammonia is allowed 

 to act upon the iodide, the more iodine is removed, and hence the 

 more oxide of lead formed. To test this, two portions were taken 

 and the ammonia allowed to act on one for 38 hours (heating it on 

 the water bath) ; on the second 68 hours. The analyses were as 

 follows : 



1. Substance heated 38 hours gave 74.10 p. c. Pb. 



2. Substance heated 68 hours gave 78-94 " " 



Calculated for Pblg. 3PbO 73-26 p. c. P6 ; for Pblg. 4PbO 76.38 p. c Pb. ; 



for Pblg. 5 PbO 79.31 p. c. Pb. 



These experiments then would lead to the following conclusions : 



1. By the action of ammonia in the cold the monobasic oxyiodide 

 of lead is formed. 



2. By heating the solution we get oxyiodides, the basicity of which 

 is determined by the length of heating. If, by the more active boiling 

 upon the sand-bath, the ammonia solution becomes weak, then the 



