the characteristic Properties of Tannin. 71 



email portion of nitric acid and subsequent evaporation, be- 

 came converted into that variety of tanning matter which is 

 produced by the action of nitric acid upon carbonaceous 

 Substances. I have since extended these experiments, and 

 shall here give some account of them, 



1 . 200 grains of the fresh peels of horse chestnuts were 

 digested for about 12 hours in three ounces of dtstilled water. 

 The liquor was of a pale brown, and formed a slight 

 pale brown precipitate when solution of isinglass was added 

 to it. 



2. 200 grains of the same peels were moderately loastcd, 

 and being afterwards digested with three ounces of water, 

 formed a dark brown decoction, which was not rendered 

 lurbid by gelatine. 



3. The above-mentioned roasted peels, after the termina- 

 tion of the preceding experiment, were adde<5 to the re- 

 mainder of the filtrated liquor. A quarter of an ounce of 

 nitric acid was poured upon the whole, which was then di- 

 gested and evaporated to dryness. The mass was afterwards 

 infused in water, and a dark reddish-brown liquid was ob-^ 

 tained, which copiously precipitated solution of isinglass. 



4. 200 grains of horse chestnuts, from which the peels 

 employed in the former experiments had been taken, were 

 bruised, and were digested with tliree ounces of walt;r. The 

 liquor was turbid, and of a pale red coloitr. It was fil- 

 trated, and some solution of isinglass was addtjd, but with- 

 out any effect. 



5. 200 grains of the same horse chestnuts were moderately 

 roasted, aiid being treated as above described with w*ater, 

 yielded a dark brown decoction which was not rendered tur- 

 bid by isinglass. 



6. The horse chestnuts, which had been employed in the 

 preceding experinitnt with the remaining lujuor, were di- 

 gested with a quarter of an ounce of nitric acid until the 

 whole was become dry. Water was then poured upon it, 

 was digested, and a dark brown liquid was formed, which 

 Jifforded a considerable precipitate by the addition of solu- 

 tion of ibin<_dass. 



Iroui these cxf>erimenls it appearp, that the small portion 

 L 4 of 



