476 PROCEEDINGS OF THE AMERICAN ACADEMY 



Analysis 3. In this analysis, in which I was prevented from deter- 

 mining the carbon, 0.1537 of bi-sulphide of carbon gave 0.9461 of sul- 

 phate of baryta, corresponding to 84.5 per cent of sulphur. 



The mixture of asbestos and peroxide of lead employed was of that 

 which had already been used in the preceding analyses, and may possi- 

 bly have contained a trace of undecomposed sulphate of lead, as the per 

 cent of sulphur found in this case is 0.3 per cent above, while in the 

 preceding analyses it was a fraction below the theoretical quantity. 

 Trusting, however, that the results already obtained will be deemed suf- 

 ficient to show the method to be a good one, I have not thought it ad- 

 visable at this time to further repeat the analysis of this substance. I 

 may here state that I have already applied the process in the analysis 

 of bodies containing hydrogen, and have obtained satisfactory results 

 which will soon be published. 



The important advantage thus gained of being able to determine the 

 different elements from the same portion of substance, considering also 

 the simplicity of the process, can hardly fail, I think, to secure for this 

 the preference over the older methods. 



Five Iiundred and forty-ninth Meeting. 



March 28, 1865. — Special Meeting. 



The President in the chair. 



Professor Gibbs presented the following paper. 



Observations on Crystals and Precipitates in Blowpipe Beads. 

 By George H. Emerson. 



Believing that the subject of this article is so far novel, at least, as 

 not to have been brought into general notice through the press, I have 

 thought it of sufficient interest to merit publication. 



While studying, a few months since, the blowpipe behavior of the 

 alkaline earths, I noticed that the opacity produced by " flaming," or 

 exposing to an intermittent heat, a borax bead sufficiently saturated 

 with one of the earths, was often only partial, — a variable portion of the 

 bead becoming opaque white, while the remainder was perfectly trans- 

 parent. The extent of the opacity seemed dependent on the duration 

 of the heat. Moreover, when nearly the whole surface was obscured, 



