CHEMISTRY. 219 



sulphur ore is poured in tlirough a funnel at one end of the cylin- 

 der, and when it has sufficiently undergone the action of the ap- 

 paratus it is led out at tiie other end. The t(;mporature in the 

 cylinder is maintained by hot air or steam, whic^h is introduced 

 under a pressure of 3 atmospheres. B}' this machine loO cubic 

 metres of the mineral are reported to be disposed of in 24 hours. 

 This economical method of extracting sulphur from its minerals is 

 a matter of great importance to Italy, which is so rich in that 

 valuable substance. 



TO ELECTRO-PLATE PAPER OR OTHER FIBROUS MATERIAL. 



A mode has been devised for depositing copper, silver, or gold, 

 by the electric process, upon paper or any other fibrous material. 

 This is accomplished by first rendering the paper a good conduc- 

 tor of electricity, without coating it with any material which will 

 peel off. One of the best methods is to take a solution of nitrate 

 of silver, pour in liquid ammonia till the precipitate formed at first 

 is entirely dissolved again ; then place the paper, silk, or muslin, 

 for one or two hours in this solution. After taking it out and 

 drying well, it is exposed to a current of hydrogen gas, by which 

 operation the silver is reduced to a metallic state, and the mate- 

 rial becomes so good a conductor of electricity that it may be 

 electro-plated with coi^per, silver, or gold in the usual manner. 

 Material prepared in this manner may be employed for various 

 useful and ornamental purposes. 



POISONOUS HOSIERY. 



The '* British Medical Journal" publishes the following inter- 

 esting note on Arsenic in Aniline Colors from Professor Wanklyn, 

 of the London Institution. It indicates clearly enough the source 

 of skin-poisoning in magenta-colored socks : — 



•'It is generally known that some of the old crude magenta 

 cake and liquor which was in the market some few years ago, 

 shortly after the first bringing out of the dye, was largely contam- 

 inated with arsenic. But it is not generally known, even to chen:i- 

 ists, that much of the beautifully crystallized magenta used to 

 consist of arseniate of roseine, being not, properly speaking, con- 

 taminated with arsenic, but actually consisting of an arsenical 

 compound. In the early part of 1863 (assisted by Mr. Robinson, 

 who was my assistant at that time), I made an examination of the 

 beautifully crystallized magenta which was being manufactured 

 in one of the largest coal-tar color works in Europe, and found 

 it to be arseniate of roseine, apparently chemically pure." 



SWEET PRINCIPLE OF FROZEN POTATOES. 



Dr. Adolph Ott has been examining frozen potatoes for the pur- 

 pose of confirming or disproving the truth of the common theory. 



