38 PROCEEDIxNGS OF THE AMERICAN ACADEMY 



Tins point in our investigation was reached in the spring of 187G, 

 and the results given above were presented to the American Academy 

 of Arts and Sciences at their meeting of June 14th, 1876.* But 

 although they agreed so closely with the results of Schneider, and 

 although the close confirmation of his analysis thus furnished by our 

 sj^u thesis seemed so conclusive, yet we could not rest satisfied so long 

 as the great discrepancy between this value of the atomic weight and 

 the higher number obtained by Dumas remained unexplained. We 

 therefore determined to repeat his experiments before publishing our 

 results. Accordingly, in the autumn of 1876, we purified and analyzed 

 a large number of different specimens of autimonious cldoride, and the 

 i-esults are united in the following table. Beginning with crystallized 

 chloride of antimony obtained from different dealers, and pure in a 

 commercial sense, we first boiled for several hours the melted chloride 

 over finely pulverized metallic antimony, using for the purpose a glass 

 retort, so tilted that the condensed liquid flowed bac-k into tlie body of 

 the vessel. When boiled in this way, the surface of tlie vapor is marked 

 by a very well-defined ring in the neck of the retort ; and by regu- 

 lating the lamp this ring can readily be maintained very near the 

 mouth, so that, while all the chloride of antimony condenses and flows 

 back, any more volatile admixtures will gradually escape. The" retort 

 having been brouglit into its normal position, the chloride of antimony 

 was next distilled ; and, rejecting the first and last eighth which came 

 over, the rest of the product was redistilled over strips of metallic zinc, 

 and so on three or four times, rejecting at each distillation the first and 

 last of the product. The final distillate was then still further purified 

 by repeated cr^-stallizations from fusion. As the fused mass solidifies 

 quite slowly (indicating a large loss of latent heat), it is easy to arrest 

 the process at any point, and pour off the still liquid portion from the 

 crystals which have formed. The last can then be remelted, and the 

 process repeated, and so on indefinitely as long as the material lasts. 

 In this way, from several kilogrammes of the commercial chloride we 

 obtained the few grammes of beautifully clear and perfect crystals used 

 in our analyses. In the fifth preparation, the crystals were obtained not 

 by fusion, but by cooling a saturated solution of the previously distilled 

 chloride in purified sulphide of carbon. Such a solution, saturated at 

 the boiling point of sulphide of carbon, deposits the larger part of the , 

 chloride, when cooled to the ordinary temperature. Naturally, every 

 precaution was taken during the course of these preparations to protect 



* These Proceedings, vol. xii. p. 282. 



