OF ARTS AND SCIENCES. 13 



Properties. — The substance crystallizes from dilute alcohol in yel- 

 lowish white narrow plates, sometimes half a centimeter in length 

 which are made up of needles attached to another needle acting as a 

 midrib at very acute angles, giving an exact imitation of a feather or 

 more commonly of one side of a feather ; this form is very character- 

 istic, and, when not so well developed, the substance can be recognized 

 by the formation of narrow plates, usually smooth on one' side and 

 rather irregularly serrated on the other, or upon the ends. The plates 

 often occur in radiating groups, the members of which form very acute 

 angles with each other. From methyl alcohol or ether it crystallizes 

 in very slender needles, much branched at very sharp angles, often 

 forming circular groups resembling certain seaweeds. It melts at 1 70° , 

 is not very soluble in cold alcohol, freely in hot, more soluble in methyl 

 than in ethyl alcohol, freely soluble in glacial acetic acid or acetone, 

 tolerably soluble in ether, slightly soluble in benzol either cold or hot, 

 or in carbonic disulphide, slightly soluble in cold chloroform, more 

 soluble but not freely in hot, nearly insoluble but not quite so in cold 

 water, more soluble but still very slightly in hot, essentially insoluble 

 in ligroine. The best solvent for it is chloroform, or a mixture of 

 alcohol and water. Its behavior with alkalis is very characteristic. 

 If a drop of an aqueous solution of sodic hydrate is added to the sub- 

 stance dissolved in alcohol, the solution takes on a dark but brilliant 

 Prussian green color. This solution becomes colorless on addition of 

 hydrochloric acid, but turns green again on addition of sodic hydrate. 

 The green alcoholic solution, if allowed to evaporate spontaneously, 

 leaves a brownish yellow residue, and a solution of the same brown- 

 ish yellow color is obtained if an excess of sodic hydrate is added to 

 the original substance. If the yellow solution, in whichever way pre- 

 pared, is acidified with hydrochloric acid, it loses its color, and oil-drops 

 are precipitated, which solidify in time. These dissolve in sodic hy- 

 drate with a brownish claret * or pale magenta color, which is unal- 

 tered by dilution with water, but turns green on addition of alcohol. 

 The substance melting at 170° is not affected by an aqueous solution of 

 sodic carbonate. The further study of these interesting reactions has 

 been broken off by the summer vacation, but will be continued in thi- 

 laboratory in the autnmn. 



* A somewhat similar change of color was observed during the action "i 

 ethylbromide on the sodium salt of the bromdinitrophenylmalonic ester. 



