1815.] Scientific Inlelligence. 237 



the Gas Light Companies force the gas through the pipes, I boo* to 

 inform him that, from its very compressible nature, and the number 

 of collateral branches from the main to the lamps, forming so many 

 outlets, that it is sent through the pipes with a very small pressure : 

 I believe of not more than equal to a column of water of one inch 

 in height. Should you consider the above worth inserting, 1 shall 

 send you a paper on the structure of the cells of wasps and bees, 

 which 1 consider so different as to require a particular explanation. 



I remain. Sir, yours truly, 



R.W. 

 XIII. Mr. Accum's Treatise on Gas Light. 



Mr. Accum has in the press a Treatise on Gas Light, exhibiting 

 a summary description of the apparatus and machinery best calcu- 

 lated for illuminating houses, streets, and public edifices, with 

 carbureted hydrogen, or coal gas ; together with remarks on the 

 utility, safety, and general' nature of this new branch of civil 

 economy. 



The treatise will be illustrated with geometrical and perspective 

 designs, exhibiting the larger gas light apparatus now successfully 

 employed for lighting the streets and houses of this metropolis, as 

 well as the smaller apparatus used by certain manufacturers and 

 private individuals, together with other objects connected with this 

 new art of illumination. 



XIV. Metallization of Charcoal. 



Mr. Dobereincr, Professor of Chemistry at the University of 

 Jena, in Saxony, informs Mr. Accum that he has discovered charcoal 

 to be a metallic substance. The following statement has been 

 received from Mr. Doberciner by Mr. Accum : — 



" 1 hope soon to be able to communicate to you the successful 

 metallization of charcoal, which 1 have reason to believe to be a 

 metallic substance; in cast-iron and in steel the metal which it 

 contains is present in a metallic state, and may be separated from 

 both of them by the united action of phosphorus and an alkali." 



Farther particulars concerning this subject Professor Dobereiner 

 promises to communicate in his next. 



XV. On the Octahedral Form of Iodine. 



(To J)r. Thomson.) 

 DEAR SIR, 



I regret that I was not aware of your intention to notice my 

 observations on the crystals of iodine, as I would have undertaken 

 to define with more precision the primary Ibrin from which all itb 

 other modifications may be readily inferred. 



You have stattjd, {Annals for Jan. p. 12,) that it assumes an 

 octtihcdral form, which, though true, is liable to be misinterpreted; 

 since the crystal may be su|)posed equilateral and equiangular, un- 

 less its peculiar deviation from the regular octohedrpn be specified. 



