SCIENTIFIC SUMMARY. 
379 
Thus it is poisonous to animal life when inhaled in any considerable quantity, 
and it destroys almost all vegetable colours, by depriving them of their 
oxygen. Heretofore the methods adopted for the removal of this compound 
from coal-gas were inadequate, and the result was that all — even the purest — 
forms of gas contained this impurity in greater or lesser proportions. The 
new method has been devised by Mr. Lewis Thomson, a gentleman already 
well known for the importance of his gas researches. Briefly, his process is 
as follows : — After the gas has left the hydraulic main, and before it reaches 
the condenser, it is mixed with a suitable quantity of steam (superheated or 
not}, and the mixture is passed through a retort or tube heated to 1200 
Fahr. The shape of the retort is not of much importance, but it appears that 
the elliptical form possesses advantages over the cylindrical, and that a cast- 
iron vessel is better than a clay one. The length of the tube (or retort) must 
be proportioned to the velocity of the current passing through it. When the 
two vapours — bisulphide of carbon and steam — are allowed to react upon 
each other in this way, mutual decomposition is effected ; the carbon of the 
sulphide abstracts oxygen, and becomes converted into carbonic acid, while 
the sulphur and hydrogen unite to form sulphuretted hydrogen, which can 
afterwards be removed. The decomposition is thus represented : — 
CS. -f 2HO = CO. + 2HS 
Sulphide of Water. Carbonic Sulphuretted 
Carbon. acid. Hydrogen. 
Vide Neiuton^s Journal of Arts and Sciences, February. 
New Mordant for Aniline Dyes. — It is reported that this long-wished-for 
substance has at last been discovered. It consists of acetate of alumina and 
arseniate of soda ; and its discoverer, Herr Schultz, believes that it will even- 
tually replace albumen, gluten, tannin, and the various other substances 
now employed for a similar purpose. To prepare the mordant, Herr Schultz 
mixes, at an ordinary temperature, four grammes of ordinary aniline violet in 
powder, with a quarter of a litre of acetate of alumina and twenty grammes 
of arseniate of soda, which he thickens with starch boiled in water. In the 
case of prints it is recommended to mix the arseniate of soda and acetate of 
alumina with the colouring matter, and to steam the fabric over the mixtui'e. 
For dyeing, it is said to be better to treat the tissue in the first place with a 
mixture of the two salts, and afterwards to dip it in the colour- vat in the 
usual way. — Vide The Artizan, January. 
Danger in Preparing Oxygen. — Those who are in the habit of preparing 
oxygen on a large scale — as, for example, for oxyhydrogen lamp purposes — 
will do well to examine the mixture v/hich is sold in commerce ' as chlo- 
rate of potash and black oxide of manganese. A very serious accident 
occurred lately from the employment of an adulterated specimen of this 
powder, in which charcoal had been partially substituted for binoxide of 
manganese. By combining (mechanically) charcoal with chlorate of potash, 
a substance having much the appearance of the genuine article is produced ; 
but this mixture is as dangerously explosive as gunpowder, and a few months 
ago caused the death of two individuals (Mr. Cro^vther, of Manchester, and 
his son) who were engaged m the preparation of oxygen gas. 
