CHEMICAL SCIENCE. 215 



Centralblatt." The specimens examined weighed from 1.86 to 

 4-65 grains, the specific gravity, whicla was ascertained bj^ floating 

 them in alcohol of known density, varying between 0.9285 for the 

 transparent and 0.9234 for the opaque hailstones. Tested for 

 nitrous acid with Schonbein's iodide of starch papers, a negative 

 result was obtained, in spite of the great sensitiveness of the jja- 

 pers. 1,000,000 parts of hail were found to contain 3.247 of am- 

 monia and 0.526 jmrts of nitric acid. This agrees tolerably well 

 with Boussingault's analyses, Avhich gave in 1,000 parts of rain- 

 water 2.16 pai'ts of ammonia. 



To Detect Sulpliuric Acid in Vinegar. — If into pure vinegar 

 starch is introduced, then the adding of a minute portion of iodine 

 will change its color to a blue tint ; but, if sulphuric acid is pres- 

 ent, no such reaction will take place, for the resultant of starch in 

 its presence is glucose, a substance not affected by iodine. 



RuhicUum and Ccesium. — Schrbtter has devised a new process by 

 which both the above metals, and lithium as well as thallium, may 

 be readily extracted from the lej^idolite of Moravia and the mica 

 of Zinnwald. It consists in transforming and separating them in 

 the form of alums, by their diiference of solubility in water. By 

 this method, the first trials, on a large scale, yielded, from a ton 

 of mica, 62 lbs. of carbonate of lithia, and 13 lbs. of the mixed 

 chlorides of rubidium and coesium, together with an appreciable 

 quantity of thallium. 



Excellent and Cheap Ink. — Dissolve in about 4 gallons of hot 

 water 3 ounces of solid extract of logwood ; to this add ^ ounce 

 of bichromate of potash, dissolved likewise in a little hot water. 

 As soon as the liquids are mingled, they assume an intense purple- 

 ish-blue color, and the ink thus prepared may be used at once ; it 

 acquires a black color on the paper while drying, and does not 

 corrode steel pens, and does not fade. The cost of materials is 

 about three cents per gallon. 



New Green Pigment. — Vogel describes a new color, "Green 

 Cinnabar," which is prepared in the following way : Prussian 

 blue is dissolved in oxalic acid ; chromate of potash is added to 

 the solution, which is then precipitated with acetate of lead. 

 The i:)recipitate, well-washed, dried, and levigated, gives a beau- 

 tiful green powder. By varying the proportions of the three 

 solutions, various shades of green may be procured. Chloride of 

 barium or nitrate of bismuth may be used in place of sugar of 

 lead. 



Solution of Silk. — A solution of silk may be made by boiling 

 it with a concentrated solution of chloride of zinc over an excess 

 of oxide of the same metal, until it no longer discolors the tinct- 

 ure of litmus. By dialysis, the silk may be obtained again in a 

 colorless inodorous form. 



Test for Cane Sugar. — H. Leplay obsei-ves that the sugar of 

 grapes blackens bichloride of carbon, while cane sugar does not. 

 — Les Mondes, Dec. 14, 1865. 



Artificial Cold. — Mr. Clowes finds that when sulpho-cyanide of 

 ammonium is dissolved in water, intense cold is produced in a 

 short time, the atmospheric moisture being deposited like hoar 



