good a quality as possible. The arrowroot, which is the most extensively adulterated of the three, was tested both by means of the vapor of iodine and the microscope, so that no doubt might exist of its being a pure article. "The determinations were made in the following manner. The different specimens were dried in watch-glasses at a temperature of 100° C. (212° F.), and were all dried for the water determinations in their market condition, with the exception of maccaroni, which seemed likely to offer so much resistance to the escape of moisture, that it was pulverized previously to drying. They were then all pulverized, thoroughly dried at the same temperature (100° C.), and the determinations of carbon, hydrogen, and nitrogen made. The combustions for carbon and hydrogen were effected in the usual manner with oxide of copper, the portion of oxide of copper at the extremity of the tube being intimately mixed with very finely pulverized chlorate of potassa. The nitrogen was determined as ammonio-chloride of platinum by ignition with soda-lime, according to the method of Varrentrapp and Will. As the amount of nitrogen was exceedingly small in most of the specimens, it was supposed that the chloride of ammonium produced in the hydrochloric acid employed, by the absorption of ammonia from the air, might produce a perceptible effect upon the results of the analyses. Coincident determinations were therefore made with the hydrochloric acid in every analysis, by evaporating portions of acid and bichloride of platinum equal to those actually employed in determining the results of the combustions, collecting the precipitate on a weighed filter as usual, washing with alcohol, &c. It was found, however, in every case, that the filter lost more from washing with alcohol than it gained by the precipitate; it was therefore necessary to make a small addition, generally about 0.0014 grm. to the amount of ammonio-chloride of platinum obtained from the combustion. In making a statement of the results, the nitrogen was taken as the basis of the calculation; carbon, hydrogen, oxygen, and sulphur were distributed to it according to the proportions indicated by the formula of nitrogenous bodies. Albumen and gluten agree with each other so nearly in constitution, as given in the analyses of Scheerer (Ann. der Chem. und Pharm., XL. 38), of Mulder, and of Rüling (Ann. der Chem. und Pharm., LVIII. 310), that a single formula has been taken, namely, that of Mulder: :- The percentage of phosphorus being so small, it has been neglected in the estimations. 12 "The carbon computed by the foregoing formula, deducted from the total amount, afforded a basis for calculating the starch, and as the numerous experiments of Horsford and Krocker have shown so conclusively that the amount of starch may be accurately calculated in this way, no doubt can be reasonably felt with regard to the justice of so doing. Hydrogen and oxygen are accordingly distributed to the carbon, according to the formula C12 H10 O10. This being done, a balance of hydrogen remained in every case. It was conceived that this was probably due to the fact that the starches cannot be deprived of all their moisture at 100° C.; part is also probably owing to moisture absorbed by the starch whilst weighing, as starch dried at 100° C. is exceedingly hygroscopic, "taking up in a few days exposed to the air 35 per cent. of moisture." (Knapp.) This hydrogen was therefore supplied with oxygen according to the formula of water. It will be seen by consulting the results, that the amount of moisture thus obtained is often quite large, and has a very considerable effect upon the averages. It is on this account, perhaps, somewhat to be regretted that the moisture was not determined at 120° or 125° C., instead of 100° C. "No. I. CORN-STARCH, No. 1. "Corn-starch is prepared from maize or Indian corn, by the aid either of the ordinary method of steeping and fermenting, or else by steeping the corn, both before and after grinding, in a caustic or carbonated alkaline lye, the gluten remaining dissolved in the lye. This specimen was in the state of fine powder. I. 0.869 grm. gave at 100° C. 0.1392 grm. loss. II. 1.127 grm. dried at 100° C. left 0.0038 grm. ash. IV. 0.3124 grm. gave 0.5017 grm. CO2 and 0.1857 grm. HO. V. 0.4468 grm. gave 0.7246 grm. CO, and 0.271 grm. VII. 1.9168 grm. gave 0.032 grm. NH,Cl. PtCl2. HO. "This specimen differed from No. 1 in being made into lumps in the state in which wheat-starch is usually sold; it yielded nearly three times as much nitrogen as No. 1, and was therefore not so pure a starch, but better fitted for the purposes of nutrition. Of its manufacture, I was unable to obtain any information. I. 3.1531 grm. lost at 100° C. 0.3748 grm. II. 2.508 grm. dried at 100° C. gave 0.011 grm. ash. III. 0.3189 grm. gave 0.508 grm. CO, and 0.187 grm. IV. 1.2677 grm. gave 0.0761 grm. NH,Cl. PtCl2. Corresponding in 100 parts to Carbon Hydrogen HO. I. 43.44 6.51 "Tapioca is a modification of starch, being partially converted into gum by heating. It is prepared from the root of the Jatropha manihot, found in the West Indies, South America, and Africa. The roots are washed, reduced to pulp, and subjected to strong pressure, by which means they are deprived of nearly all their highly poisonous juice. As the active principle of this juice is volatile, it is entirely dissipated by baking the pulp upon iron plates. The pulp thus prepared is hard and friable, and is easily broken into lumps, which are laid in the sun to dry. In this state it is known by the name of cassava. It is puri. fied by being stirred up with water and filtered through linen; the liquid is then boiled down over a fire, being constantly kept in agitation. As the water evaporates the starch thickens, and finally becomes granulated, when it must be dried over a stove. A tolerably good imitation of it is made by treating potato-starch in a similar manner. I. 1.0577 grm. lost at 100° C. 0.1409 grm. II. 1.383 grm. dried at 100° C. left 0.0016 grm. ash. Estimated in 100 parts, we obtain the following numbers: |