234 ANNUAL OF SCIENTIFIC DISCOVERY. 



dissolved consists of interposed sulphur, which is removed after 

 dessication by a solution of caustic soda ; there then remains the least 

 aggregated and least resistant organic substance, which is yellowish and 

 translucent. The undissolved portion then remains under the form of 

 q, tenacious strip, which has become brown and less transparent. The 

 following are the proportions obtained, besides the fatty matter : tena- 

 cious insoluble portion, 65 ; soft soluble portion, 25; sulphur in excess, 10. 



The process of vulcanization in the cold way, invented by Mr. 

 Parker, of England, consists in immersing the sheets, or tubes of 

 caoutchouc in a mixture of 100 parts of sulphuret of carbon, and 2.5 

 protochloride of sulphur. The liquid in penetrating into the organic 

 substance, swells it, and deposits the sulphur, which combines with the 

 caoutchouc, abandoning the unstable combination which it formed in 

 the chloride. The superficial portion would be too strongly vulcan- 

 ized and become brittle, if these objects were not removed in one or 

 two minutes, and immediately immersed in water. In this case the 

 chloride of sulphur, decomposed by its contact with the water, ceases 

 to act on the surface, while the portions which have entered farther in 

 continue their sulphurizing action on the interior. This is an ingen- 

 ious means of regulating this kind of vulcanization by the cold way. 



A process, which seemsstill more preferable, as regards the healthi- 

 ness and regularity of the operation, is due to the same inventor. It 

 is effected by keeping the objects to be vulcanized immersed for two or 

 three hours in close vessels, in a solution of 25 Baume, of polysul- 

 phuret of potassium, at a temperature of 284 Fahr., and submitting to 

 a washing in an alkaline solution, and then in pure water. We are 

 thus enabled to combine caoutchouc with a useful proportion of 

 sulphur, without allowing an excess of it to be interposed in its pores, 

 thus avoiding the inconveniences of the unequal sulphurization of the 

 organic substance. 



COMPOSITION FOR SILVERING GLASS. 



PREPARE a mixture of 30 grains ammonia, 60 grains nitrate of 

 silver, 90 grains spirit of wine, and 90 grains of water. When the 

 nitrate of silver is completely dissolved, filter the liquid and add a 

 small quantity of sugar, for example, 15 grains of the grape sugar 

 previously dissolved in a mixture of 1 ounces of water, and 1^ 

 ounces spirit of wine. 



For silvering a glass it is sufficient to leave this solution in contact 

 with the glass during two or three days. Civil Engineer and Archi- 

 tect's Journal. 



PREPARATION OF PURE METHYLIC ALCOHOL. 



WOHLER has given a very simple and elegant method of preparing 

 pure wood-spirit from the raw material of commerce, which is of 

 interest both to the chemist and pharmaceutist. Raw wood-spirit is to 

 be mixed with an equal weight of sulphuric acid, avoiding an elevation 



