water. 



374 ANALYSIS OF THE HUSKS OF WALNUTS. 



latter, if in excess, enters into combination. It is proba- 

 ble, that the sulphuric acid combines with the tanning mat- 

 ter, without expelling the nitric acid. 

 Earthy matter 43. The liquor from which the tanning matter had been 

 of the coal, and precipitated by acetate of lead having had sulphuretted hi- 

 drogen passed through it, and been afterward filtered, con- 

 yellow bitter tained the earthy matters of the coal, and a yellow bitter 

 matter. matter, the nature of which I could not positively as- 



certain. 

 Brown matter 44. I dissolved the brown matter I have mentioned (40) 

 jMdJWein in nitric acid at 45° [sp.gr. 1-435], concentrated the so- 

 lution, and afterward added water to it. This precipitated 

 a yellowish substance, similar in appearance to the matter 

 A, separated by water from a nitric solution of pitcoal: 

 but the yellowish substance differs from A in being entirely 

 soluble in boiling water, and in not being fusible by heat. 

 I presume, that it differs from the portion soluble in water 

 (41) only in containing less nitric acid, and perhaps more 

 hidrogen. 



XI. 



Chemical Examination of the Husks of Walnuts. By Mr, 

 Henry Bkaconnot, Prof, of Nat. Hist. 4 - c«* 



Husks of wal- JL HE daily use of the husks of walnuts in the art of dye- 

 nuts used in j n „ suggested to me the wish of making some experiments 

 dyeing. 



t on them, to be enabled to form a more accurate judgment 



of their nature. 



Soon changed When fresh the husk is interiorly white, but it becomes 

 coloured very quickly, and ultimately passes to a dark 

 brown. This is owing to the contact of the air; for, if it 



unless kept be immersed in water that has been boiled, it will keep 



from air. some time without undergoing the least change. If it be 



Apparently a . -., , . , , . , . 



slow combus- placed in a jar filled with atmospheric air, the oxigen will 



tion effected. soon be converted almost wholly into carbonic acid; the 

 husk acquires a blackish colour; and no doubt there is also 

 a production of water: so that the whole seems to indicate 



. 

 * Ann. deChim. vol. LXXIV, p. 303. 



the 



