46 RE POET — 1875. 



Besearclies on (lie Crystalline Constituents of Aloes*. 

 B>j \YiLLiAiM A. TiLDEN, D.Sc. Lotid., F.C.S. 



Barbaloin is the name given to the aloiu from Barbadoes aloes. It is a yellow, 

 soluble, crystalline body, wliich yields substitution compounds witli chlorine, 

 bromine, and acetyl. Zanaloin (from Zanzibar aloes) is supposed to be identical 

 "with Socaloin (from Socotrine aloes), because the two compounds give the same 

 qualitative reactions ; but the latter has not been analyzed. Zanaloin, after drjang 

 in a vacuum, gives the same numbers as Barbaloin, the results of analysis in each 

 case agreeing with the formula C,(. Hj, 0_. Zanaloin also yields substitution deriva- 

 tives, the two series of isomeric compounds being expressed by the formulfe 



C.JI^.Ol^O,, 

 C,,H,/Br.3 0,; ■ 

 C,„ 11,3 (C,H3 0)30, 



Zanaloin is distinguishable from Barbaloin by the action of strong nitric acid, 

 wliich gives a crimson coloration with the latter; whilst with the former very 

 slight change is manifest till heat is applied, when a bright orange-red colour is 

 developed. 



JS^ote on Miintz and Samspachers Apparatus for tlie Estimation of Tannic 

 Acid. Bxj JoHJsr Watts, D.Sc. 



The following avrangement was devised by MM. Mihitz and Ramspacher in order 

 to ascertain with accuracy the actual Icather-prodiiciiic/ power of an astringent sub- 

 stance, which, according to the experience of the manufactm'er, does not appear 

 always to coincide with its percentage of tannic acid. 



The apparatus may be briefly described as a shallow gim-metal drum of about 

 200 cubic ceutinis. capacity, permanently closed ot one end by an india-rubber 

 plate, and capable of being closed watertight at the other by a piece of depilated 

 hide when clamped upon a stand over which the hide has been previously stretched. 

 The drum is perforated at the side with a screw to admit of the introduction of the 

 tanning liquor, and is fitted above with a screw-piston to compress the india-rubber 

 disk. When the piston is lowered the liquor is forced through the hide, while the 

 latter retains the whole of the tannic acid. The density of the liquor is taken 

 b.ifore and after the operation by means of a very fine hj'drometer graduated to a 

 special scale, when the difference expresses at once the percentage value of the 

 liquor operated on. 



The advantages of the arrangement will be obvious to any one who has experi- 

 ence in analj'ses of this description ; it is sufficient to say that the analysis is con- 

 ducted with ease and rapidity, and that the average variation is about 0-5 per cent. 



In order to compare the results of Eamspacher's tannometer with Hammer's 

 table of percentages of tannin in solutions of different densities, and to compare 

 both with the results of evaporation, a number of experiments were undertaken by 

 the author, as shown below. The percentages only indicate the value of the par- 

 ticular sample under examination. 



By spetific gravity. By tinnometer. By evaporation. 



Cube Gambler 41-45 4044 47-43 



Bale Gambler 42-44 39-50 4902 



Cutch 47-70 44-GO 52-16 



Valonea 25-S2 25-32 2630 



ISIvrobalanes 3230 SO-28 31-08 



Mimosa-bark 31-44 30-18 31-72 



Blue Galls GO-CO 59-10 



Green Galls 53-40 52-41 5790 



Sumach 17-10 18-00 19-55 



Divi-L)ivi 34-50 33-94 35-20 



* Published in exfttuo in the Pharm. J. Trans. (3) vi. 208. 



