Some Peculiar Double Salts of Lead 5 



metallic acetate used is comparatively readily soluble, else a 

 sufficient excess of the acetate would not be present to hold 

 the lead iodid in solution. Alcohol, either strong or, in 

 some cases, diluted with water, was found to best meet the 

 requirements, but even this would not serve in the case of 

 certain of the acetates tried, which are so slightly soluble in 

 alcohol as to necessitate the addition of too much water to 

 effect solution, the excess of water producing decomposition. 

 It was found further that the readiness with which the acetate 

 dissolves in the solvent, and, therefore, to this degree, the 

 solvent itself, plays an important part in determining the char- 

 acter and composition of the product obtained ; the reaction is 

 an excellent illustration of the influence of mass. This part of 

 the problem is being separately investigated and will appear later. 

 The Iodid-acetate of Lead. — It was stated on page 4, that, 

 when sodium acetate acts upon lead iodid a product, 



Pd^-^ -\-NaaB2O2 



is obtained, and the assumption was made that the iodid-acetate 

 of lead was formed as an intermediate product. If this assump- 

 tion is correct, it should be possible to start with the iodid- 

 acetate and cause this to unite directly with sodium acetate. 

 Carius^ prepared the iodid-acetate of lead by heating together 

 in a sealed tube at 140° C. a mixture of i mol. ethyl iodid, little 

 more than i mol. lead acetate, and i mol. glacial acetic acid. 

 Numerous attempts were made to repeat Carius's work, using 

 the utmost precaution, and also by varying the conditions, but up 

 to the present without obtaining the product described by him. A 

 reaction evidently takes place, and in some cases small quan- 

 tities of a white, crystalline substance were obtained, but 

 generally, long before the reaction could have completed 

 itself, lead iodid began to form and crystallize out, and in such 

 quantities as to preclude the possibility of securing the white, 

 crystalline mass in a fit condition for analysis.- This made it 



iZ. c, p. 89. 



2 Some further experiments, made just as this paper was being pre- 

 pared for publication, indicate tha possibility of obtaining a pure product, 

 whether iodid-acetate or not yet remains to be determined. 



311 



