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Tannic acid precipitates it, both from aqueous and alcoholic solutions, but lead salts and mercuric chloride do not affect it. It does not reduce ammonio nitrate of silver.

158. SARSAPARILLIN. A colorless solid, crystallizable in needles; soluble in water and in alcohol, soluble in ether and in volatile oils. The solutions froth when shaken. Strong sulphuric acid dissolves it with deep red color, changing to violet and finally to yellow. From this solution water precipitates it unaltered.

159. TARAXACIN. Crystallizes in warty masses, of a pleasant bitter taste, fusible, and soluble in water, alcohol, ether, and in concentrated acids.

160. VANILLIN. CH,O,. Crystallizes in long, colorless, four-sided prisms, melting at 76° C. (or 82° C.), distilling with vapor of water, and subliming in part at 150° C. It is neutral in reaction, and has the characteristic odor of vanilla. It is nearly insoluble in cold, moderately soluble in hot water, freely soluble in alcohol, ether, and volatile oils. It dissolves in strong sulphuric acid and in potassa.

161. Separation of the Glucosides and Neutral Compounds-described in 144-160-by Water, Alcohol, Ether, and Aqueous Alkalies (recapitulation):

a. Water dissolves Absinthin (sparingly), Aloin (hot, sparingly), Amygdalin, Asparagin, Cathartin, Columbin (sparingly), Cubebin (slightly), Fraxin, Lactucin, Phloridzin, Populin (sparingly), Quassin (sparingly), Sarsaparillin, Taraxacin, Vanillin (slightly). Water does not dissolve Cantharidin, Cubebin (except slight portions), Elaterin, Vanillin (except slight portions).

b. Alcohol dissolves Absinthin, Aloin, Amygdalin, Cantharidin (sparingly), Colombin (sparingly), Cubebin (sparingly), Elaterin, Fraxin, Lactucin, Phloridzin, Populin (sparingly), Quassin, Sarsaparillin, Taraxacin, Vanillin.-Alcohol does not dissolve Asparagin, Cathartin.

c. Ether dissolves Absinthin, Aloin (sparingly), Cantharidin, Cubebin, Elaterin (sparingly), Lactucin (sparingly), Sarsaparillin, Taraxacin, Vanillin.-Ether does not dissolve Amygdalin, Asparagin, Fraxin (except slight portions), Phloridzin, Populin, Quassin (except slight portions).

d. Aqueous alkalies dissolve Absinthin, Aloin, Asparagin, Cathartin, Colombin, Phloridzin, Populin, Vanillin; do not dissolve Cubebin.

[For Dragendorff's elaborate process for separation and identification of Foreign Bitters in Beer, see Arch. Pharm. (3), iii., 295; iv., 389; or Jour. Chem. Soc., 1874, p. 818; or Prescott's Exam. Alcoholic Liquors, N. Y., 1874.]

NITROGENOUS NEUTRAL BODIES.

162. ALBUMENOIDS.

Varieties of Albumen, Fibrin, and Casein.-Characterized as infusible, non-volatile, amorphous solids, neutral in reaction and indifferent to combination; in natural condition, soluble in water containing alkalies or containing certain salts of alkalies; rendered insoluble in water by acids, and generally by heat in absence of dissolving agents, and by salts of certain heavy metals. Farther, they give a reaction for nitrogen (a), and color-tests with strong hydrochloric acid (b), and with mercuric nitrate in nitric acid (c), and act as reducing agents (d).-Albumenoids are distinguished and partly separated from Gelatin, Gums, and Dextrin, by their coagulation with heat or with mineral acids; they are separated from starch by dissolving in solution of alkali too dilute to affect the starch (see 176, f).

a. Mix the well-dried substance with dry soda-lime, introduce into a hard-glass long-necked matrass (or long and narrow test-tube), place a slip of red litmus-paper in the mouth, and heat, gradually, to incipient carbonization. Production of ammonia (this base being absent in the substance) indicates a nitro

genous organic body.-Albumenoids, on boiling with potassa solution, yield ammonia; a farther quantity being obtained by adding permanganate (WANKLYN).

b. Strongest hydrochloric acid dissolves albumenoids to a yellowish color, which becomes blue or violet by exposure to the air.

c. Acid mercuric nitrate solution-prepared by dissolving one part of mercury in two parts of nitric acid of spec. grav. 1.42 -on digestion with solid albumenoids, at 60° to 100° C. (140° to 212° F.), gives a deep red color. If the substance tested is in solution, it should be concentrated, and used in such small proportion that the reagent is not much diluted.

d. Alkaline cupric solution is turned violet by albumenoids, and on warming the cuprous oxide is quickly reduced. Solution of permanganate is also reduced by albumenoids.

Under the Microscope, albumenoids are turned yellow by iodine, and purple-violet by sulphuric acid with sugar.

163. OVALBumen. Soluble in water with some turbidity and suspension of skinny particles; this solution being rendered nearly clear by alkalies or alkaline carbonates or common salt.— Chemically neutral water solutions are coagulated by heating to a very little above 63° C. (145° F.); by alcohol, carbolic acid, and creosote; by ether (but not completely), by nitric acid (quickly and completely), by hydrochloric acid (slowly redissolving when the acid is strong), and by sulphuric acid (slowly). Salts of silver, mercury, etc., coagulate it; also alum. Acetic and tribasic phosphoric acids do not coagulate it, but (by neutralizing the natural alkali) they render its pure water solution still more turbid. Tannic acid coagulates it quickly.-Strong potassa, 'or soda, gelatinizes albumen.

For weighing, albumen is precipitated from slightly acidulated solutions by boiling, washed with water, and dried first below 50° C. (122° F.), then at 100° C. (So treated, it is not rendered insoluble.)

164. SERALbumen,

Dissolves in water with some turbidity.

Coagulated at 75° C. (167° F.), or, in presence of alkaline salts, at a higher temperature, while in presence of acetic acid a lower temperature suffices. Coagulated by dilute mineral acids, slowly or if heated quickly; redissolved by strong nitric acid and (readily) by hydrochloric acid. Coagulated by alcohol; not by ether (distinction from Ovalbumen).-Coagulated by salts of mercury and silver.—Aqueous alkalies dissolve coagulated seralbumen.

165. CASEIN. In natural condition, dissolved clear by water. Coagulated by rennet (separation from milk albumen); by moderately dilute acetic acid (separation from ovalbumen, seralbumen, milk albumen); by ether and by mineral acids and mercuric chloride. Not coagulated by dilute alcohol or by boiling (separation from seralbumen and from ovalbumen). Alkalies and strong acids, even strong acetic acid, dissolve coagulated casein. [Farther, see Phar. Jour., 1874, Sept. 5, p. 188.]

166. MILK ALBUMEN. (0.3 to 0.5 per cent. of healthy cows' milk; found as high as 3 to 10 per cent. in diseased milk and in the colostrum.)—Not coagulated by rennet, but coagulated by boiling, after the slightest acidulation with acetic acid (two means of separation from Casein). Coagulated by mineral acids and salts of heavy metals; the coagulum being soluble in alkalies.

167. Determination of Casein and Albumen in Milk.a. Take 50 grams of milk, add an equal quantity of water, add rennet, set aside at 40° to 50° C. Gather the precipitate (the casein with most of the fats) in a tared filter, wash with water, then with alcohol, then with ether thoroughly, dry at 110° C., and weigh as Casein.-To the filtrate from the curd (and first water washings), add 4 or 5 drops of acetic acid and boil. Gather the coagulum in a tared filter, wash with water, dry at 110° C., and weigh as Albumen.—(The filtrate from the curd of albumen is saved for determination of the Sugar, according to 187, l. This filtrate contains a minute proportion of an albumenoid called Lacto-protein, which is coagulated by mercuric nitrate -not by nitric acid.)

168. Quantitative Analysis of Milk.

(1) Determine the Total Solids, as directed in 64, b.
(2) Determine the Fats, as directed in 64, b (or a).

(3) Determine the Casein and Albumen, as directed in 167. (4) Determine the Sugar, from the filtrate of 167, according to 187, l.

(5) Determine the Salts (soluble and insoluble in water). Evaporate 20 grams in a tared dish, with a tared small glass rod, ignite to whiteness (by triturating); weigh, then extract with water and dry and weigh the residue.

169. Commercial Examinations of Milk usually require, more especially, the following operations :

(1) Find the volume per cent. of cream. scope-64, c.)

(Or use a lacto

(2) Take the specific gravity, and consider the relation between this and the amount of cream. Skimmed milk has a specific gravity about 0.004 greater than entire milk (from CHANDLER'S averages.)

(3) For more exact data, find the solids minus futs, as directed in (1) and (2) of 168. The "solids not fat” is nearly the same proportion of the milk of different cows-also, of the whole milk, the skim milk, and the cream, alike (WANKLYN). Hence, variation in this quantity indicates sophistication.

(4) Examine with the microscope (presence of colostrum globules usually coinciding with excess of albumen), and test for impurities in general.

170. GELATIN. (Isinglass, Glue, "Gelatin.") An infusible, non-volatile, amorphous, horny solid; colorless to yellowish, translucent, brittle, odorless, and tasteless.-Characterized as a neutral and indifferent substance, evolving ammonia freely when heated dry with soda-lime or when boiled with potassa solution and permanganate (see Albumenoids, 162, a), and existing in a soluble and an insoluble condition. Its soluble form dissolves very slowly and slightly in cold water, gradually

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