1872.] Chemical Science. 513 
prevalent, and the assistance offered to young and aspiring experimentalists, 
though great, was ineffectual. Dr. Gladstone concluded his Address by 
alluding to the magnificent liberality of Mr. J. B. Lawes, who has made over 
his laboratory of Agricultural Chemistry to trustees, and endowed it, for the 
benefit of science, with the sum of £100,000. 
Professor Williamson proposed and Dr. Longstaff seconded the vote of 
thanks to the President. 
Essential Oils —Dr. Gladstone, Dr. Wright, and Mr. W. C. Roberts, of the 
Mint, read a paper on the results of their experiments on the composition of 
some essential oils used in perfumes, in which it appeared that the choice of 
the sample greatly affected the value of the result. 
The Fusion of Arsenic.—Prof. Mallet reported the successful fusion of ar- 
senic in narrow glass tubing (barometer tubing) enclosed in an outer tube of 
iron, and heated in a charcoal fire. Arsenic thus treated appears, on cooling, 
as a fused, compact, crystalline mass, of steel-grey colour, and has a sp. gr. 
of 5*70g at 15° C. The fusing-point is between that of antimony and silver. 
Prof. Mallet exhibited also three specimens of meteoric iron from Augusta 
Co., Virginia. 
British Gold Coinage.—Mr. W. Chandler Roberts, the Chemist of the Mint, 
detailed the precautions taken to ensure accuracy in the preparation of the 
gold-copper alloy, an account of which has appeared already in these pages. 
Decomposition of Water.—On a subsequent day Dr. Gladstone read a paper 
on the *‘ Mutual Helpfulness of Chemical Affinity, Heat, and Eledtricity, in 
producing the Decomposition of Water.” Only certain of the metals are ca- 
pable of displacing the hydrogen of pure water. Pure zinc does not do so, 
but does so when the chemical tension is aided by the electrical tension set up 
when the zinc is the positive plate of a voltaic couple. The effect of varying 
the distance between the plates of zinc and copper was commented upon, and 
it was stated that the chemical action increased slowly till the plates are 
within an inch or so of each other; nearer the action increases at a rapidly 
accelerating ratio. Heat assists the action. Magnesium alone decomposes 
water, but more vigorously when in contact with copper, upon which some of 
the hydrogen gas makes its appearance. If a more negative metal than mag- 
nesium be employed in contac with an again more negative metal, there is 
still a deflection of the galvanometer employed to measure the amount of 
action. The order for pure water seems to be—platinum, silver, copper, iron, 
tin, lead, zinc, magnesium. 
Manufacture of Chlorine—Mr. Weldon read a paper on his process of 
manufacturing chlorine by means of manganite of magnesium. The inventor 
employs a still to yield an absolutely neutral still-liquor, consisting of a mixed 
solution of chloride of magnesium and chloride of manganese. The liquor is 
conveyed from the still to an iron pot, whence it is pumped or syphoned into 
evaporating-pans, and thence again into a blind furnace, where the evaporation 
is continued todryness. The residue is then gently heated with access of air, 
the chlorine of the two chlorides being driven off, partly free and partly as hy- 
drochloric acid, and manganite of magnesium produced. The loss during the 
process is merely mechanical, the chemical loss being absolutely nz. 
After this paper Dr. Crace Calvert read an interesting report on bleaching- 
powders, with the idea of promoting useful discussion. 
Ignition of Cellulose by Saturation with Fatty Oils.—Prof. Dewar read a 
paper, by Mr. John Galletly, on the “‘ Danger of Ignition of Rags, Paper, &c., 
Saturated with Oil,” and it was shown that cotton-waste, saturated with either 
boiled linseed oil, raw linseed oil, rape oil, Galipoli oil, castor oil, lard oil, or 
seal oil, and confined in a closed chamber, became, after from 1o hours to 
100 minutes, ignited to ash completely, or more or less charred. Sperm oil 
refused to char the waste. The cause assigned is rapid oxidation, and the 
author submits that the term ‘‘spontaneous combustion”? may be objected to 
for the same reason that Gerhardt objeéts to spontaneous decomposition pro- 
duced by oxidation. Heavy oils from coal and shale, chiefly the olefines, 
VOL. II. (N.S.) 3U 
