CHEMICAL SCIENCE. 225 



gen, but which may be averted by boiling with a solution of bichromate of 

 potassa acidulated with sulphuric acid. 



The phosphuret of copper which resists this latter agent is decomposed, 

 although slowly, when it is boiled with hydrochloric acid; the products of 

 the reaction are uninflammable gas and chloride of copper. However, this 

 phosphuret may inflame spontaneously when exposed to the solar rays. 

 This, at least, is what happened to M. Boettger in placing the crude phos- 

 phorus in the sun for the purpose of drying it. 



NEW METHOD OF PREPARING SULPHUROUS ACID. BY 



E. F. ANTHON. 



The author placed two ounces of sulphur, in fragments, and twenty-five 

 ounces of concentrated sulphuric acid, into a glass flask, furnished with a 

 gas tube, and heated it over a spirit-lamp. The sulphur soon melted, and 

 in a short time there was an evolution of sulphurous acid, which was con- 

 ducted into water. The evolution was very uniform, and the burning of the 

 spirit-lamp was continued until, after about six hours, there was only a com- 

 paratively small residue in the flask. 



During this treatment, the sulphur constantly floated in the form of a 

 transparent hyacinth-red, thickly fluid mass on the hot sulphuric acid, and a 

 small portion of it sublimed ; part of this condensed again in drops upon the 

 walls of the flask, and flowed back into the acid, whilst another part was 

 deposited in the form of a thin crust in the neck of the flask. Very small 

 quantities of sulphur were carried further mechanically by the sulphurous 

 acid, and deposited in the connecting tube. At the conclusion of the process, 

 the flask contained only 4} drachms of sulphuric acid and 32 grains of unal- 

 tered sulphur. 



The advantages of this process are: that it furnishes a pure product; that 

 it is easily and cheaply effected; the evolution of the sulphurous acid gas is 

 very uniform ; and no solid deposit settles at the bottom of the vessel of 

 evolution, which, in other methods, so often occasions the cracking of the 

 vessel. Dingier' s Journal, c. 1. p. 379. 



COAL-TAR ITS COMPOSITION AND ITS APPLICATIONS. 



The following popularly-written article contains a summary of what has 

 been effected, during the last few years, in the treatment and application of 

 "coal-tar" and its products. 



Every reader is perfectly familiar with the color, odor, and generally disa- 

 greeable nature of tar. We don't mean the rich, fragrant, foreign fluid, pre- 

 pared from the roots and otherwise useless portions of resinous firs, and 

 known as Stockholm tar; nor yet the purer extract furnished by the wood- 

 vinegar or pyroligneous acid maker. These are tars, but they are not our 

 tar: our tar is far more disagreeable than any other kind, and is usually 

 called, in allusion to the source whence it is obtained, coal-tar. 



Coal-tar is torn from the long embrace of its parent coal, at the period 

 when that parent yields up to the service of man a no less cherished off- 

 spring, gas. As coal is heated in confined chambers, the carburetted hydro- 

 gen, for the production of which the operation is performed, is separated, 

 and with it a quantity of the black treacley -looking fluid known as tar. This 

 is collected in proper receptacles, and as it is of no use to the gas manufac- 

 turer, is sold to those whose special business is its preparation. 



