DYEING AND CALICO PRINTING .

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on the chemistry of drying oils more generally known, undoubtedly these oilswould, in course of time, be extensively substituted for albumen.

Qualitative Testing of Albumen.

Dissolve about 5 grms. of the dried albumen in cold, pure water, in which,if itself is pure, it should be perfectly soluble. Add a few drops of aceticacid and filter the solution. There may remain insoluble, coagulatedalbumen, caseine, and membranous matter; the caseine may be dissolved bytreating the insoluble residue with a weak solution of caustic soda, whenceit is again thrown down by acetic acid. The clear filtrate is boiled, thedissolved albumen being coagulated and thrown down as a flocculent pre-cipitate. This precipitate is now removed by filtration, and to the filtrate isadded a solution of tannic acid in water in order to precipitate any gelatinewhich might be present. Alcohol may next be added to precipitate gum anddextrine.

Quantitative Estimation of Albumen.

The only important point is to ascertain the quantity of albumen coagulableby heat, and this may be estimated by dissolving a weighed quantity, say5 grms., of the sample in water, adding a few drops of acetic acid, filteringif required, and boiling the filtrate for some time. The coagulated albumenmay then be collected upon a previously weighed filter, washed with boilingwater, again with alcohol and ether, dried at ioo° C., and weighed.

If a volumetric method be preferred, the following, by M. Scheurer-Kestner,will be found advantageous:—The solution of the sample is diluted to half alitre. From this 100 c.c. are taken, to which 10 c.c. of sulphuric acid areadded. Two standard solutions are required, one containing permanganateof potash, the other protochloride of iron, so diluted that one volume of theiron solution discolours or decomposes exadlly one volume of the perman-ganate solution. The protochloride of iron solution may be obtained bydissolving 2 grms. of pure iron (pianoforte wire) in pure hydrochloric acid,and diluting the solution to a litre. The permanganate solution is adjustedto the iron solution volume for volume. • Further, there is required a standardsolution of pure albumen containing 10 grms. to the litre. The relation ofthis solution to the permanganate solution should also be accurately adjusted.According to M. Thierry-Miey, this method gives excellent results within5 P er cent; but the gravimetrical method together with qualitative analysisappears to be better suited to the estimation of the quantity of albumencontained in a given sample.

Caseine, Fibrine, and Gluten.

Caseine is the chief nitrogenised constituent of milk. Milk, containingabout 12 per cent of solid matter, 3 per cent of which is caseine,agrees in many of its chemical properties and its elementary compositionwith albumen. Milk is not a solution ; but the chief of its solid constituentsare in a state of minute division, and the diversity of its solid constituentsgreatly aids this mechanical admixture. Caseine, as contained in milk, iscombined with soda, forming therewith an albuminate identical with thealbuminate obtained when previously coagulated albumen combines with soda.