22 ^ MESSRS. DALE AND SCHORLEMMER ON THE 



a reddish brown crystalline powder. The same properties 

 are shown by the crystals obtained from acetyl chloride 

 and those obtained from Mr. Lowe. When heated to iio° 

 in a current of dry air^ they gradually lose all the acetic 

 acid (which plays the part of water of crystallization) and 

 assume a dull red colour. 



On passing hydrochloric acid gas into an alcoholic so- 

 lution of aurin^ similar but smaller needles are formed, 

 containing alcohol, which is given off at ioo°j the dull red 

 residue can, like the preceding one, be heated to 190° in a 

 current of dry air without losing hydrochloric acid, which 

 only begins to escape at 200°. 



Analysis of these compounds showed that the dried sub- 

 stance consists of CjgHj^OjjHCl, while the crystals obtained 

 from an acetic-acid solution have the composition Cj^Hj^Oj, 

 HCl + iCH^O,, and those from alcohol 2Cj^H,g03,HCl + 

 3aH,0. 



When sulphuric acid is added to a hot alcoholic solution 

 of aurin, small red needles are formed on cooling, which 

 consist of (0,511,403)2,80411^ + alcohol. Under the same 

 conditions an acetic-acid solution yields fine prismatic 

 crystals, or flat very glistening needles, which are an acid 

 sulphate, its formula being C^^H^ ^0^,^0^112, + acetic acid. 



We have also prepared a nitrate (which is readily formed 

 and crystallizes well), but have not analyzed it yet. 



In our first communication to the Chemical Society we 

 described a compound of aurin and sulphur dioxide, which 

 is easily obtained in bright-red crystals by passing sulphur 

 dioxide into a saturated alcoholic solution of aurin. Our 

 former observation, that this body contains water but no 

 alcohol, we found confirmed. On heating it decomposition 

 easily takes place, pure aurin being left behind ; but it ap- 

 pears to be quite stable when exposed to the air ; and even 

 on heating it with water, no sulphur dioxide is given ofi"; 



