218 ANNUAL OF SCIENTIFIC DISCOA'ERT. 



but can be manufactured to any extent. There seems no practical 

 difficult}^ in the use of these salts, and we hope that a trial of them 

 will be made in this country. The city of Calcutta, in India, is 

 about to test the method. The dust is said to be intolerable 

 there, and of a most damaging nature to clothing, etc., as the 

 roads are made of brick, easily pulverized by the feet of horses 

 and the wheels of vehicles. — Scientific American, etc. 



THE ELECTROLYSIS OF WATER. 



A curious, and, if correct, important paper on the electrolysis 

 of water h^s been published by M. Bourgouin. Pure water, he 

 states, is never decomposed by electrolysis, whatever the strength 

 of the battery employed, or however long the attempt may be per- 

 severed in. Sulphuric acid or an alkali is always added to enable, 

 it is said, the water to conduct electricity. His experiments, how- 

 ever, go to show that these bodies perform a more important part 

 than mere conducting agents. When potash was employed, he 

 observed that the amount of hydrogen disengaged was alwa5-s 

 proportional to the amount of potassium carried to the negative 

 pole, and his opinion is that it is a hydrate of potassium, K HO2, 

 which is decomposed. Similarl}^ in the case of water acidulated 

 with sulphuric acid, he believes that a hydrate, S HsOe, is the 

 body electrol3"zed, and that the excess of water takes no further 

 part in the action than to continually replace that removed from 

 the compound named. — Mechanics' Magazine, 



EXTRACTION OF SULPHUR. 



An entirely new process is just reported to have been introduced 

 into Italy by M. Brunfaut, a Belgian. The average composition 

 of the sulphur-stone of the Romagna is, for every 100 parts, 30.60 

 of sulphur, 26.80 of lime, 41.20 of alumina and silica, and 1.40 of 

 water. By the ordinary method of extraction, only 10 of the 30 

 parts of sulphur are obtained. There is, therefore, a loss of up- 

 wards of 20 per cent., which, of course, must influence not only 

 the profits, but also the price of the article. These defects in the 

 system appear to have been completely obviated by M. Brunfaut, 

 v\iio is said to have obtained a yield of 25 per cent, instead of 10. 



As already observed, the sulphur is contained only in a state of 

 mixture in the Romagna stone, and, not being in chemical combi- 

 nation with any substance, is easily separated by fusion. The 

 melting-point of sulphur being extremely low, fusion may be ef- 

 fected by hot air or by steam, instead of in kilns or even heaps, 

 where the excess of heat converts a large portion of the substance 

 into sulphurous acid. Taking advantage of this property of sul- 

 phur, M. Brunfaut employs an apparatus which consists of a hori- 

 zontal cylinder containing an Archimedean screw throughout its 

 whole length. The cylinder is made to revolve more or less 

 slowly, according to the nature of the mineral to be treated. The 



