D. CHEMISTRY AND' METALLURGY. 77 



equivalents of water. In a word, this insoluble substance 

 has as much affinity for moisture as deliquescent salts. But 

 one of the most curious features in connection with this extra- 

 ordinary phenomenon is that, on being dried at 2i2 F.,bigal- 

 late of antimony loses the two equivalents of water which it 

 had absorbed from the air, and that, on being left exposed 

 once more to the atmosphere, it reabsorbs the same amount 

 of moisture. This interesting experiment may be repeated 

 indefinitely. 15 A, November 11, 1871, 628. 



ACRIDINE, A NEW ANTHRACENE DERIVATIVE. 



A basic substance has lately been separated by Graebe and 

 Caro from crude anthracene, to which, on account of its irri- 

 tating action upon the skin and mucous membranes, they 

 have given the name of acridine. This body is obtained by 

 heating the semi-solid portion of coal naphtha, which boils 

 between 300 and 360, with dilute sulphuric acid, and pre- 

 cipitating the acid solution with potassium dichroraate. A 

 dirty brown precipitate is obtained, which dissolves on re- 

 peated treatment with boiling water. The solution thus ob- 

 tained yields, after filtration and cooling, orange-yellow crys- 

 tals of the chromate of the base; these crystals, freed from 

 the mother-liquor by washing, yield the free base when warm- 

 ed with 'ammonia. Thus obtained, the body is not quite pure ; 

 but it may be rendered so by recrystallizing its hydrochlo- 

 ride. Acridine substance crystallizes, as determined by Dr. 

 P. Groth, in small, four-sided, rectangular prisms of the rhom- 

 bic system, whose edges are often, but narrowly, truncated 

 by the vertical prism, while the ends are formed by obtuse 

 domes. 



Acridine melts at 10*7, and distills without alteration at a 

 temperature above 360. It sublimes, even below its melt- 

 ing-point, in Jarge, broad needles. It is almost insoluble in 

 cold, and but little soluble in boiling water. On the other 

 hand, it dissolves readily in alcohol, ether, carbon-bisulphide, 

 and hydro-carbons. The dilute solutions show* a beautiful 

 blue color by reflected light. It exerts a slight but distinct 

 alkaline reaction on litmus. When inhaled, either in dust or 

 vapor, it causes sneezing, and, in large quantity, coughing. 

 It is exceedingly stable, and may be distilled unaltered over 

 either ignited zinc or soda-lime, although most readily at- 



