Comparative Analysis of the Gum Resins. 349 
and the liquor was long im’ passing’ through it.’ Care was 
taken to wash well im boiling water the substance’ which 
would not dissolve. Towed ) 
C. The liquor when evaporated “to “dryness ‘left 23 
grammes of a red transparent gum; and of a bitter taste. 
1. This gum reddens turnsole.tinetares?°> 015" 
2. When treated with boiling water, “it only “dissolved 
in part, and there remained: a substance‘of a gummy ap- 
pearance, perfectly insoluble even in the weak acids. It 
occupied a great deal of room, became brittle‘after’ desic- 
cation, and swelled afterwards in boiling water without 
being dissolved in it. This insolubility which is acquired 
by gum myrrh seems to be owing to heat. te 
3. Gum myrrh when distilled, furnished’ subacetate of 
ammonia, oil, and a charcoal, which was iticmerated very 
easily in comparison with those of animal sabstances. 
4, When treated by the weak nitric “aeid, this’ gum 
produced with the help of a gentle heat carbonie acid gas 
mixed with azotic gas: there was deposited a flaky yellow 
matter which soon disappeared: the liquid when evaporated 
to dryness left oxalic acid mixed with malic acid, as well 
as a bitter yellow matter which does not detonate. 
5. The oxalate of potash produces a precipitate of oxa- 
late of lime in the solution of gum myrrh. 
6. Lime-water in excess does. not affect the transparency, 
which indicates that it contains neither malic acid nor 
phosphoric acid. 
7. The decoction of gall-nuts does not produce any 
change; and this is the case also with liquid oxygenated 
muriatic acid. 
8. Several metallic solutions, such as those of lead, mer- 
cury, tin, precipitate this gum from its aqueous solvent: 
very abundant white sediments are the result. 
The precipitate produced by the nitrate of lead in 23 
grammes of this gum dissolved in water, weighed 20 
grammes 2 decivramines, after desiccation. Jt was of a 
reddish colour like myrrh,and was semi-transparent: boiling 
water did not divide it; but upon gradually adding weak 
sulphuric acid until there was a slight excess, the grumous 
particles disappeared, and it was filtered. There remained 
upon the filter well washed and dried 5°3 grammes of 
“sulphate of lead containing 4 grammes of oxide, which was 
combined with 16 grammes of gum-imyrrh, which I ob- 
tained by evaporating the liquor separated from the sul- 
phate of lead. This gum, which held an excess of acid, did 
not give malic or phosphoric acid on treating it with es 
iol, 
