312 Communicalions respecting 
mination of hydrocyanic; its combinations with the bases, that 
of hydrocyanates; and the coinbinations of its radical, that of 
eyanures. 
We would fain give an account of the numerous and delieate 
experiments by which M. Gay-Lussac referred to the oue or 
the other of these classes the various products resulting from 
the action of the prussic acid on bodies, and all the properties 
which he has brought to light; but our limits do not admit of 
it. Suffice it to say, that Prussian blue in particular seems to 
him to be rather a cyanure of iron which has retained water, 
than a hydrocyunat, or, as it was formerly called, a prussiate. 
This ey anogene, considered by itself, presented some remarka- 
ble properties: it is a permanent elastic fluid, the density of which 
to that of the air is as |. 8U64 to J, of a peculiar pinigent smell, 
giving a sharp taste to water, and burning with a purpie flame, 
Water absorbs four times its vohime, aud ‘alebhil 23: its direct 
analysis gave the same result with that of the hydrocyanic acid, 
Z. es one volume of vapour of carbon for half a volume of azote. 
[lo be continued. | 
LXIII. Intelligence and Miscellaneous Articles. 
QOMMUNICATIONS RESPECTING SIR H. DAVY’S SAFE-LAMP. 
Havine learnt by the Newcastle newspapers that a deputation 
from the coal-owners of the rivers Tyne and Wear, &c. had 
waited on Sir Humphry Davy, on his return from Scotland 
through Newcastle, in the end of March, to express to him 
their opinion of the merits of his invention for guarding the 
lives of miners against the effects of fire-damp explosions, and 
to thank him for the benefits thus conferred on humanity ; we 
were anxious to be enabled to give all the publicity in our power 
to such an unquestionable testimony, as being the most satis- 
factory reply to the animadversions which appeared in another 
periodical work on the observations which we have before made 
on this most important discovery. We could not for obvious 
reasons request Sir Humphry to furnish us with the documents 
wanted. We applied to the chairman of the meeting alluded to, 
d our reqnest met with that prompt attention which we an- 
Picipates. The facts are briefly these: A deputation from the 
coal-owners addressed the following note 
* To Sir H, Davy, Se. Be. Se. 
** Messrs. Lamb, Brown, Potts, Watson, Cronden, Waldie, 
Jas. Lamb, and Buddle, forming a deputation from the coal- 
owners of the rivers Tyne and Wear, and the ports of ate 
: an 
