Prof. Brodie on the Atomic Weight of Graphite. 539 



The following Table contains a similar summary of the results 

 upon cyliudrical yessels : — 



The paper includes an investigation of the laws of collapse as 

 exhibited in these results, and the following general formula; are 

 obtained : — 



For glass globes P= 28,300,000 x ~, 



For glass cylinders 



P= 740,000 X 





where P = the collapsing pressure in pounds per square inch ; 

 k = thickness in inches ; D and L = diameter and length re- 

 spectively in inches. 



These are the general formulae for glass vessels subjected to an 

 external pressure, and the latter is precisely similar to that found 

 for sheet-iron cylinders. 



Transverse Strenx/th of Glass. — The authors derive the general 

 formula 



W=3140x ^^, 



where W = breaking weight in pounds, K = area of transverse sec- 

 tion, D = depth of section, I = length between supports ; — to express 

 the transverse strength of a rectangular bar of glass supported at 

 the ends and loaded at the middle. 



*' On the Atomic Weight of Graphite." By Benjamin C. Brodie, 

 Esq., F.R.S., Pres. C.S., Professor of Chemistry in the University 

 of Oxford. 



In this paper the author arrives at the following results : — That 

 carbon in the form of graphite forms a system of peculiar com- 

 pounds, different from any compounds of carbon yet known, and 

 capable of being jtrocured only from graphite. Tliat graphite, 

 within certain limits, functions as a distinct element, capable indeed 

 of being converted by certain processes of oxidation into carbonic 



t Remained unbroken. 



