cent. of B-bengucopaloresene, C22H36O2, insoluble in ether; and 3 to 4 per cent. of essential oil. Bengucopalic acid is removed from the ether solution of the resin by shaking out with 1 per cent. Na2CO3 solution. It melts at 134-136°C., and is isomeric of congocopalic acid, m.p. 115-118°C.; a-congopaloresene and essential oil remain in the ether solution. Bengucopalolic acid is obtained by shaking out the alcohol-ether solution of the resin with 1 per cent. K2CO3 solution; this removes the acid which is soluble in ether and also ẞ-bengucopaloresene, which is insoluble.

Comparison of the formulae of the hitherto isolated copalresin-acids shows their relationship and also their affinity to the conifer-resin acids, thus :-Congocopalic acid, C19H3002; bengucopalic acid, C19H30O2; bengucopalolic acid, C21H3203 ; congocopalolic acid, C22H3403; angocopalolic acid, C23H3603; kamerucopalolic acid, C21H36O3; trachylolic acid, C21H3603.

Bengucopalolic, congocopalolic and angocopalolic acids are homologues.

Copals, Manila and Pontianak. C. Coffignier. (Bull. Soc. Chim. [4], 3, 453.) Manila copal.-Manila copal occurs in three varieties, hard, semi-hard and friable. The hard variety occurs in large pieces, varying in colour from dull white to brown. The pieces break easily with a brilliant fracture; some pieces are milky inside; the odour is aromatic. The white form had the sp. gr. 1.065; m.p. 190°C. (softening at 80°C.); acid value, 72-8; Koettstorfer value, 87.

The friable variety also occurs in aromatic pieces of varying colour, readily broken, with a fairly brilliant fracture. Sp. gr., 1060; m.p. 120°C. (softening at 45°); acid value, 145.2; Koettstorfer value, 185∙1.

Pontianak copal derives its name from a province in Borneo. It occurs in bulky pieces, generally transparent, but some are milky. The colour varies from bright yellow to brown. The fracture is slightly brilliant and sometimes moist; the odour is aromatic, resembling that of elemi. The resin is easily powdered. Sp. gr., 1-037; m.p. 135°C. (softening at 55°C.); acid value, 134-3; Koettstorfer value, 186-5. The behaviour of the three varieties towards solvents is indicated in the following table, in which the figures represent the percentage of insoluble resin per cent., in the solvent named, at the boiling temperature :—

It will be seen from the above that Pontianak copal closely resembles friable Manila in properties.

Copper, Method for Determining, in Preserved Vegetables. C. Brebeck. (Zeits. fur Unters. Nahr. genussm., 13, 548; Nouveaux Remèdes, 23, 126.) After draining, the vegetables are dried by rolling in a cloth. 50 Gm. of material is then weighed off and dried on a filter paper in a Petri dish at 105°C. in a stove. The dried material is then incinerated in a capacious porcelain capsule, and the filter paper burnt as well. The ash is then treated with strong HCl and the solution obtained is filtered. The insoluble residue and filter are dried, again incinerated, treated afresh with HCl and filtered. The filtrate is added to that at first obtained. The bulked acid liquid is evaporated, the residue is taken up with water acidified with HCl, the solution treated with excess of AmOH, and filtered, and the precipitate washed. The filtrate and washings are then concentrated in a tared Pt dish, the residue is treated with HCl, and a fragment of Zn is added. The Cu is then deposited on the Pt; reduction is terminated when a trace of the liquid gives no red colour with K,FeCy, reagent. The capsule is then carefully washed, first with water, then with alcohol, and finally dried at 100°. The increase of weight is due to Cu.

Manieli.

Cubebin, Constitution of the Molecule of. E. (Pharm. Zeit., 53, 109; Chem. Zeit., 1908 [4].) Pure cubebin, m.p. 132°C., has the empirical formula C20H 2006 and is represented thus

H2C

[C&Ha(OH)2]

CH2.

The structure of the CH, group in the connecting molecule between the two piperonyl nuclei has not yet been determined.

Daucus carota Fruits, Essential Oil of. (Schimmels' Report, October, 1907, 31.) The German-grown fruits of Daucus carota yielded 1.26 per cent. of a brownish yellow oil, sp. gr. 0.9440 at 15°C.; a-13°5'; acid value, 2-2; ester value, 17-8; acetyl value, 77.5; soluble 1: 1.8 and more alcohol 80 per cent. These characters differ from those of oil distilled in 1902, and from oil of French carrot fruit distilled in 1904.

Dextrophenylglucosazone, Melting Point of. F. Tutin. (Proc. Chem. Soc., 23, 251.) The osazones of the sugars contained in a large number of plants were found, when purified by solution in a small volume of pyridine, hot alcohol, and subsequently a little water, and crystallizing, to have m.p.s' ranging from 216° to 218°C., which is markedly higher than 205°C., the m.p. generally attributed to dextrophenylglucosazone. Such osazone with the m.p. 205°C. was found, however, when purified as above, to melt at 217°C. A further specimen of the osazone, prepared from dextrose and freshly distilled phenylhydrazine, and avoiding a too protracted period of heating, had the initial m.p. 216°C. The correct m.p. of dextrophenylglucosazone is therefore about 217°C., and not

205°C.

Diastase, Method for Determining, in Various Preparations. W. A. Johnson. (Journ. Amer. Chem. Soc., 30, 798.) A routine starch-iodine method, employing standard potato starch and conducting the experiments at the constant temperature 40°C., is advocated. The standard starch is thus prepared: 500 Gm. of potato starch is repeatedly washed with distilled water, by decantation, then sucked as dry as possible on a Buchner funnel. The mass is then spread on glass plates and dried 3 hours in an air current at a temperature of 50°C. It is then rubbed down in a mortar, after which it is dried at 80°C. for 4 hours, which reduces the moisture to 9.5 per cent., when the product is rubbed up again and bottled. It is not advisable to try to dry beyond 90 per cent. of pure starch,

as the anhydrous starch absorbs moisture so quickly as to introduce inaccuracies in weighing. Prepared in this way the microscopic examination shows clean granules, free from fracture and free from foreign substances. Corn starch is wholly unsuited for this purpose. From the above pure starch, the starch paste required is made thus: 22-22 Gm. (equivalent to 20 Gm. of anhydrous starch), is stirred to a uniform cream with 100 c.c. of water; this is poured into 800 c.c. of boiling water in a tared flask; the mixture is boiled for 10 minutes, then more water is added to make the weight 100 Gm. It is then heated and well shaken up. For each test quantities of 50 Gm. each are weighed into a series of flasks, clamped in a large water-bath kept at 40°C.

The iodine test solution is made by dissolving 2 Gm. of iodine and 4 Gm. of KI in 250 c.c. of water. 2 c.c. of this solution

are then diluted with distilled water to make 1,000 c.c.

In making up the diastase solutions, the operator must be guided by the results of a few preliminary experiments in each case. For liquid malt extracts, for example, 10 c.c. diluted to 100 c.c. will be generally a proper strength, while in the examination of the dry preparations on the market, 200 to 500 Mgm. dissolved or suspended in 100 c.c. of distilled water will usually answer. These solutions are used in this way.

Small definite volumes of the dilution are added to the flasks containing the starch paste in the thermostat, and with the least possible loss of time. The mixture is well shaken. The volumes added may be as follows, but all diluted to that of the largest volume before mixing: 1 c.c., 2 c.c., 3 c.c., 4 c.c., 5 c.c., 6 c.c. In about 8 minutes tests are begun by removing volumes of 5 drops of each digesting mixture by a pipette and adding this to 5 c.c. of the diluted iodine solution in a clear white test tube standing over white paper. It is best to have a row of these tubes mounted to receive the liquids to be tested, If at the end of 10 minutes drops from one of the flasks fail to give the iodine reaction, a second and more accurate test may be made. Weigh out now 100 Gm. of the paste into each of six bottles and, assuming that the end point was found in the first test to be between 4 and 5 c.c., add accurately to the different flasks these volumes of the diastase solution : 8 c.c., 84 c.c., 8.8 c.c., 9.2 c.c., 9.6 c.c., 10 c.c. These volumes should stand ready and all diluted to 10 c.c. so that they may be poured into and shaken up with the starch without delay,

The tests with the iodine solution are repeated as in the first trial, and new limits are found between which the real value must lie. For example, at the expiration of 10 minutes the paste to which 8-8 c.c. of the diastase solution are added may show a faint yellowish dextrin colour, while that with the 9.2 C.C. is colourless. For all practical purposes it is not necessary to go go beyond this. In fact, readings cannot be made to a much greater degree of accuracy because of the difficulty in distinguishing between the final shade from the disappearing erythrodextrin and the achroodextrin, using these terms in a general sense, rather than in the sense of assuming the actual existence of these forms.

Much of the uncertainty in the determination of diastatic values, as found in the literature, doubtless comes from the failure to recognize the importance of working to a colourless end point whenever this is possible. Most results for starchconverting power found advertised are evidently obtained by working to a rose-red end point, as the U.S.P. allows in the case of the pancreatin test. For this reason many of the strong products which have been examined appear to be somewhat weaker than claimed. This is shown by the results of the following table, in which the statements of digesting power are given in both ways. The diastase products tested are among the best known in the market and are widely advertised. In giving the starch-converting power of such preparations anhydrous starch does not appear to be taken as the standard in any case. Average commercial starch contains about 15 per cent. of water, which should be allowed for in making fair comparisons.