536 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ried at will, from pale gray to intense black, according to the 

 proportions of the silver and the material used as a precipi- 

 tant. In general it is black, in proportion to the affinity it 

 has for oxygen, and the degree to which it is removed from 

 the silver. The process of Mr. Vial is presented by him to 

 the consideration of scientific and practical men for their ex- 

 periments, and he feels quite sure that it will take a place of 

 great importance in the arts of printing and dyeing. 6 J5, 

 June 10, 1872, 1486. 



MINERAL SPERM-OIL. 



Mr. Hayes calls the attention of American chemists to the 

 value, for illuminating purposes, of a heavy oil obtained from 

 petroleum, and known in the trade as Morrill's mineral sperm- 

 oil. This, it is claimed, has the advantage of being as safe 

 as sperm-oil in combustion. It is sufficiently thin to fill the 

 wicks perfectly, but is so far from being a volatile oil that it 

 is comparatively inodorous, and will not take fire at any tem- 

 perature below 300 Fahr. Flames of considerable size, such 

 as a large ball of wicking-yarn, saturated with oil and ignit- 

 ed, when plunged beneath the surface of this oil, previously 

 heated to the temperature of boiling water, are extinguished 

 at once. It burns freely in the German student lamps, and 

 with great brilliancy from the " dual burner." The patentee 

 of this oil estimates that 60,000 gallons can be manufactured 

 per day, or about one fourth of the whole product of petro- 

 leum. This is more than twice the whole product of the 

 sperm and whale oils in the best days of the fishery in this 

 country. American Chemist, May, 1872, 404. 



INDIA-RUBBER CORKS. 



It is announced that India-rubber corks may be cut or 

 bored with as much facility as true cork, if the knife or cork- 

 borer be dipped m a solution of caustic potash or soda. The 

 strength of the solution is of little consequence, but should 

 not be weaker than the ordinary reagent solution. Alcohol 

 and water both answer a good purpose, but are much less ef- 

 ficacious than the soda lye ; and if a tolerably sharp knife be 

 moistened with this substance it acts upon the rubber quite 

 as easily as it would upon cork. In boring holes in rubber 

 corks, to avoid the contraction of the diameter at the bottom, 



