CHEMICAL SCIENCE. 235 



it is necessary to pass the cloth into a bath of bichloinde of mercury, com- 

 posed as follows : 



"Water, .... 100 gallons. 



Bichloride of Mercury, . 6 pounds. 

 Acetate of Soda, . 12 " 



Acetic Acid, . . .2 quarts. 



Until recently, all the green colors produced on fabrics were the results of 

 blue and yellow mixed together; but of late public attention has been 

 drawn to a green matter discovered by the Chinese, and fixed by them on 

 cotton. It has been ascertained that they prepare it, by a long and tedious 

 process, from two plants called Pa-bi-lo-za (Rhamnus chlorophorus) and 

 Hom-bi-lo-za (Rhamnus utilis), and sell it in small square cakes, under the 

 name of Luh-kaou, or Luh-chaou. The first commercial importation of 

 this color, new to us, is quite recent, as the first public sale of it in England 

 took place during the present year (18-38), under the name of China- 

 green indigo. No sooner had a foreign green substance been brought to 

 our notice, than in Europe w r e had succeeded in obtaining also a green dye- 

 ing substance from the plants which surround us; and Mr. Schlumbergcr 

 has been fortunate enough to fix on woollen fabrics the green chlorophylle, 

 or coloring matter of leaves and grass. This discovery will, in time, prove 

 of great service to dyers and calico-printers. Mr. Schlumberger's process 

 consists in boiling 60 Ibs. of grass with 25 gallons of water. This operation 

 is repeated, and the grass then treated with 25 gallons of soda lye, with 

 addition of 2 to 4 Ibs. of Mercer's dung substitute (phosphate of soda and 

 lime). Boil half an hour, and then add excess of hydrochloric acid; a 

 green precipitate falls, which is separated by filtration. The precipitate is 

 dissolved in very dilute soda lye, adding a little of the substitute, and the 

 silk or wool to be dyed is dipped in until, the desired shade is obtained. 

 Stannate of soda is the only mordant which gives any beneficial result. 



ROSOLIC ACID. 



At a recent meeting of the London Chemical Society, Dr. Hugo Miiller 

 read a paper " On Rosolic Acid." Since the discovery of this body by 

 Runge, no mention has been made of its reoccurrence, while even its existence 

 has been called in question. The author met with it accidentally, as a result 

 of the slow action of caustic lime upon the crude carbolic acid of coal-tar. 

 After long exposure to the air, the mass assumed a red color, and when 

 acted upon by water, yielded a solution of crude rosolate of lime, having a 

 fine red color. From this salt rosolic acid was obtained and purified. Its 

 empirical formula was found to be C46 Has Os. It is a very feeble acid, unit- 

 ing only with caustic alkalies and earths. "The solutions of these compounds 

 are of a most magnificent crimson color, but are very unstable. The car- 

 bonic acid of the air liberates the rosolic acid, which is eventually destroyed 

 by continued exposure to air and light. 



IMPROVEMENT IN THE MANUFACTURE OF COAL OILS. 



An invention recently patented in England, relates to a method of dis- 

 tilling coal, shale, and bituminous substances, whereby a pure oil, suitable 

 for illumination and other purposes, is obtained at the first distillation. 



It has long been known that many varieties of coal, shale, and bituminous 



