CHEMISTRY. 143 



an extended memoir on the reaction of phtbalic acid with the 

 phenols, by which the curious new class of coloring matters, 

 of which fluorescein and eosin are examples, are produced. 

 Several new bodies belonging to the phthalins and phtha- 

 leins of these phenols are described, the paper being one of 

 great interest. 



Kriiger, a German chemist, suggests the substitution of 

 fluorescein in place of litmus as an indicator in titration. 

 The beautiful fluorescence of this substance completely dis- 

 appears in the presence of the slightest trace of acid, and as 

 quickly reappears in the presence of free alkali. The changes 

 are marked and characteristic. Free carbonic and acetic 

 acids, however, do not affect the solution. The reagent can 

 readily be used with colored solutions. 



Lip p man n and Hawliczek have made an accurate compar- 

 ison between the benzoic aldehyde of bitter-almond oil, from 

 the almond, and that obtained svntheticallv from toluene. 

 The two bodies were found to be both chemically and phys- 

 ically identical. 



Gnehm some years ago discovered a new orange coloring 

 matter, dipicrylamine, or more properly hexanitrodiphenyla- 

 mine, the ammonium salt of which was, in 1874, brought into 

 commerce. But quite unexpectedly its manufacture had to 

 be intermitted because of its action upon the skin, which was 

 strongly irritating, producing an eruption resembling that 

 caused by croton-oil or tartar-emetic ointment. Finding 

 now the new coloring matter in the market under the name 

 of Aurantia, he calls attention to its poisonous properties. 

 To this, Martins, one of the Arm making it, replies, saying 

 that any such effects are due either to impurities or to the 

 idiosyncrasies of the persons poisoned, his product never 

 having given any complaint. Gnehm in his answer men- 

 tions establishments where both his coloring matter and after- 

 wards aurantia were used ; in both cases the workmen were 

 covered with the eruption of the skin spoken of. 



Dale and Schorlemmer have shown that red aurin, or 

 peonin, as it is sometimes called, may readily be converted 

 into rosaniline. If it be heated to 150 for some days with 

 alcoholic ammonia, or for twenty hours to 120 with aque- 

 ous ammonia, a yellow solution is obtained, which contains 

 a crystalline base, and deposits it on cooling. This base is 



