264> EXPERIMENTS ON ASTRINGENT VEGETABLES. 



Viroe, (Irontia, When folulion of lime, of ftrontia, or of barytes, was poured 

 cxcef^ Threw * n exce ^ ,nto a portion of the infufion, a copious olive-coloured 

 down nearly the precipitate was'formed, and the folution became almoft clear, 

 whole contents. and ^ reddifti tint. In this cafe, the tannin, the gallic acid, 

 and the extractive matter, feemed to be almofl: wholly carried 

 down in the precipitates; as the refidual fluids, when faturated 

 by an acid, gave no precipitate to gelatine, and only a very 

 flight ti«nt of purple to oxygenated fulphate of iron. 

 Effect of fmallcr When the folutions of the alkaline earths were ufed only in 

 fmall quantities, the infufion being in excefs, a fmaller quantity 

 of precipitate was formed, and the refidual liquor was of an 

 olive-green colour ; the tint being darkefl in the experiment 

 with the barytes, and lighted in that with the lime. This fluid, 

 when examined, was found to hold in folution a compound of 

 gallic acid and alkaline earth. It became turbid when acled 

 on by a little fulphuric acid ; and, after being filtrated, gave a 

 black colour with the folutions of iron, but was notacled upon 

 by gelatine. 

 Effect of lime When a large proportion of lime was heated for fome time 

 more particularly w j lh t | ie j n f u f 10Ilj j t combined with all its conftituent principles, 

 and gave, by warning, a fluid which had the tafle of lime-water, 

 and which held in folution only a very fmall quantity of ve- 

 getable matter. Its colour was pale yellow ; and, when fatu- 

 rated with muriatic acid, it did not precipitate gelatine, and 

 gave only a flight purple tinge to the folutions of the falts of 

 iron. The lime in combination with the folid matter of the 

 infufion, was of a fawn colour. It became greet) at its furface, 

 where it was expofed to the air; and, when wafhed with large 

 quantities of water, it continued to give, even to the laft por- 

 tions, a pale yellow tinge. . 

 alfo of magnefia. Magnefia was boiled in one portion of the infufion for a few 

 hours; and mixed in excefs with another portion, which was 

 fuffered to rejnain cold. In both cafes, a deep green fluid was 

 obtained, which precipitated the falts of iron, but not the folu- 

 tions of gelatine ; and the magnefia had acquired a grayifh- 

 green tint. Water poured upon it became green, and acquired 

 the properties of the fluid at fiift obtained. After long wafning, 

 the colour of the magnefia changed to dirty yellow ; and the 

 ]afl portions of water made to act upon it were pale yellow, and 

 altered very li t tie the folutions of iron. 



3 When 



