According to the method of the International Association, the apparatus shown in Fig. 66 is employed for this purpose. The glass bell is carefully and uniformly stuffed with hide-powder, care being taken that no channels are left, especially at the sides, through which the liquor can reach the syphon without traversing the hide-powder. Before filling the bell, the short leg of the syphon-tube should be loosely plugged with cotton-wool (of which a little is allowed to project from the end), in order to prevent the powder from gaining access to the tube. The powder is retained in its position in the bell by a piece of muslin held by an indiarubber band, and the bell is then placed in a beaker or tumbler as shown in the figure; and filtered liquor is gradually added, as it is absorbed by the powder, till the whole is uniformly wetted. The liquor which was first filtered through the paper, and rejected for “total solubles,” may be used for this purpose, and it is not necessary that it should be absolutely clear. The syphon is now gently sucked, and the filtrate is allowed to fall, drop by drop, into a gauged cylinder. The first 30 c.c. which collects is rejected, since it contains traces of dissolved hide-substance even from the purest hide-powder; and the next 50 c.c. should give no turbidity if a few drops are mixed either with clear tannin solution (absence of dissolved hide-substance), or with the first 30 c.c. (absence of tannin). This 50 c.c. is used for determination of non-tannins, by evaporation and drying precisely as has been described in the case of “total soluble.” Some chemists, with very accurate balances, prefer to evaporate only 25 c.c., which effects a little saving of time in evaporation; but in any case the whole of the 50 c.c. must be allowed to run through the filter before it is measured, as the filtrate varies somewhat in solid contents as the filtration proceeds. The filtration and evaporation should be done in duplicate. The weight of the residue is calculated into percentage as “soluble non-tanning matters” precisely as has been described for the “total soluble”; and when subtracted from the latter, the remainder is the percentage of “tanning matters.” If the hide-powder now employed by the English members of the International Association (manufactured by Messrs. Mehner and Stransky in Freiberg in Sachsen), be employed, no difficulty will be found in the filtration. This powder is quite neutral, and contains between 10 and 20 per cent. of cellulose to render it more absorbent. It does not swell in the filter, and hence should be stuffed into the bell almost as tightly as possible, about 10 grm. being required. If the bell is properly filled, the filtration should altogether take about one hour, but if the liquid runs too fast, it must be regulated by a pinchcock on the indiarubber tube of the syphon. If other powders are used, which often contain acid, and swell very much in