1817.] during the Year 1816. 25 
and retained its magnetic virtues in perfection. This boruret of 
jron dissolved with difficulty in muriatic acid, and boreted hydrogen 
gas was disengaged. But the gas obtained by Gmelin seems to have 
been but imperfectly saturated with boron. It had the smell of 
hydrogen gas from iron, mixed with the odour of asafoetida, and 
burned with a green flame. Neither its specific gravity, nor the 
proportion of oxygen necessary to burn it completely, were ascer- 
tained. From some experiments on the borates, which will be 
stated in a subsequent part of this historical sketch, Gmelin con- 
cludes that the weight of an atom of boron is 5°8, and that boracic 
acid is composed of 1 atom boron + 2 atoms oxygen, or of 74-4 
boron and 25°6 oxygen. (Schweigger’s Journal, xv. 245.) 
2. Charcoal.—According to Dobereiner, wood charcoal, after 
being exposed to a red heat, is a compound of A 
Carliontt) P20Us BAU ES foe. . 68-4 
Hydrogen .....-.e eee e cree e ences 1:0 
Before exposure to a red heat, its composition is— 
Carbon ...ceserscecensscrass tina eo DOA 
Hydrogen .....eeeeeereecreecerees es 
(Schweigger’s Journal, xvi. 92.) According to the same chemist, 
animal charcoal is composed of six atoms carbon and one atom azote. 
(Ibid. 86.) 
3. Gas from Coal.—Lampadius has published a set of experi- 
ments on the quantity of gas obtained by the distillation of various 
kinds of German coal, The proportions and illuminating qualities 
vary considerably; but I do not consider it as worth while to state 
the results, because no description whatever is given of the varieties 
of coal employed. ‘The experiments of course can be useful only 
to those who are acquainted with the nature of the coals which 
Lampadius used. For their advantage, I may mention that the 
experiments in question are inserted in Schweigger’s Journal, xv. 
142, published on Jan. 20, 1816. 
Mr. Brande has given some useful and amusing facts respecting 
the gas from pit coal considered as a substitute for oil. (Journal of 
the Royal Institution, i. 71.) Achaldron of good Wallsend New- 
castle coals yields from 17,000 to 20,000 cubic feet of gas; but in 
large establishments the quantity obtained seldom exceeds 12,000 
cubic feet. At the three stations belonging to the chartered Gas 
Light Company, situated in Peter-street, Westminster, Worship- 
street, aud Norton Falgate, 25 chaldrons of coals are carbonized 
daily, which yield 300,000 cubic feet of gas, equal to the supply 
of 75,000 Argand’s lamps, each giving the'light of six candles. At 
the City Gas Works, in Dorset-street, Blacktriars Bridge, the daily 
consumption of coals amounts to three chaldrons, which afford gas 
for the supply of 1500 lamps: so that the total consumption of coals 
daily in London for the purpose of illumination amounts to 28 chal- 
drons, and the number of lights supplied to 76,500. 
