84 JOURNAL OF THE 



1st Fraction contained 64.50; Pb Br,. Pb CI, has 64. 14 p. c. lead. 

 2d Fraction contained 64.76: Pb Br,. Pb CI, has 64.14 p. c lead. 

 3d Fraction contained 66.34: 2 Pb CI,. Pb Br, has 66.16 p. c. lead. 

 4th Fraction contained 69.11: 3 Pb CI,. Pb Br, has 68.97 p. c. lead. 



When it is remembered that these various crops of crystals 

 cannot be thoroughly washed and purified because of the ease 

 with which they are usually decomposed by water, and further- 

 more that there is no probability of procuring absolutely dis- 

 tinct crystallization from one fractionation, the variations between 

 calculated and observed numbers in the analyses will not appear 

 large. 



Of course it cannot be absolutely maintained from the agree- 

 ment of the analytical numbers with those for certain formulas 

 that such and such compounds were obtained. But the fact that 

 these were well-formed crystals and that not even the magnifying- 

 glass could reveal evidences of mixing lends strong probability to 

 the view that lead chloride and lead bromide have the power of 

 uniting in a great many distinct proportions, depending upon the 

 relative amounts in solution and perhaps upon other factors, such 

 as concentration and temperature. 



That the crystals were very similar in appearance in all cases 

 makes the solution of the question of the actual existence of 

 these v^arious compounds more difficult. It is hoped that some 

 other double compounds may be found which lend themselves 

 better to the decision of the question. 



LEAD BROMO-NITRATES. 



BY H. L. MILLER. 



A solution of lead nitrate, containing also some lead bromide, 

 on standing and slowly evaporating gave handsome clumps of 

 needle-like crystals very different in appearance from crystals of 

 lead bromide. Some of these were collected, washed, dried and 

 on analysis gave 33.05 j>er cent, of bromine. 



