11 



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 Strength of Glass. The authors derive the general 

 formula 



W=3140x ^5, 



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. 



II. " 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. Received May 5, 1859. 



(Abstract.) 



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 procured only from graphite. That graphite, 

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

 of being converted by certain processes of oxidation into carbonic 

 acid and thus identified with the other forms of carbon, but having 

 a distinct atomic weight, namely 33 (H=l). 



After the detail of certain experiments by which the author was 

 led to believe in the existence of a distinct system of compounds of 

 graphite, an account is given of a peculiar crystalline substance 

 formed by the prolonged oxidation of graphite. This substance 

 consists of transparent plates of a pale yellow colour, which exhibit 

 under the microscope an appearance distinctly crystalline. The ana- 

 lysis of this substance gave for its formula C n H 4 O 5 (C= 12, O= 16). 

 From the ratio of the hydrogen to the oxygen in this substance, 

 from the circumstance that it is procured from graphite alone, and 

 from its general physical properties, it is inferred that this substance 

 is the term in the system of graphite which corresponds to the 

 compound of silicon, oxygen and hydrogen, in the system of silicon, 

 procured by Wohler from the graphitoidal form of that element, 



