HARVESTING. It is hardly necessary to state that the harvesting should be carefully done. The plants are cut off close to the soil. A cloth spread upon the ground will prevent the loss of any seed that might fall. When it is not convenient to make dry matter determinations at once, such plants as the grains and legumes which are quite dry when harvested are put in large paper bags, properly marked, and hung up until wanted. Plants which are succulent when cut must first be partially dried, either in the sun or by artificial heat, otherwise they will be injured by mold. The material must also be protected from mice. When necessary, large wire closets can be constructed, which will serve as a protection and at the same time in no way interfere with the circulation of the air. Tubers, etc., are easily preserved. Whenever necessary dry matter determinations should be made at once, and proper samples preserved for future analysis. PRESERVING THE PLANT ROOTS. In the majority of cases in experiments of this kind it is seldom necessary to preserve the plant roots for analysis. Whenever this is desired, however, the entire contents of the pot are placed in a large sieve of fine wire, and by repeated immersions in water the soil washed out from the roots. After the earth has been removed as thoroughly as possible by this treatment, the siliceous material still remaining is estimated by an ash determination and the amount subtracted from the total weight of roots. ANALYSIS OF THE HARVESTED MATERIAL. It is necessary in the first place to weigh with exactness the amount of grain and straw or roots and leaves grown in each cylinder or pot. The convenient opportunity having arrived, be it at harvest time or during the winter season, the grain or seed is separated from the straw and the latter cut into small pieces with scissors, or better, with a small cutting machine. The grain and straw are then weighed separately and the results recorded as so much air-dry material. A part of the cut straw and the entire amount of the grain harvested from a single pot or cylinder (the grain without being crushed) is used for a dry matter determination. The estimation of dry matter, however, is in the majority of cases not sufficient to prove the value of a certain form of fertilizer. After the above determination, therefore, the material from each of the parallel tests, if they agree, is mixed together, an average sample taken, ground fine, and preserved in glass bottles for further examination. In order, for example, to get a correct idea of the influence of the different forms of phosphoric acid it is necessary that the amount of phosphoric acid in the harvested material at different stages of growth be estimated. A single example will make this clear. If for 10 parts of water-soluble phosphoric acid applied 100 parts increase in dry matter results, and for 10 parts of phosphoric acid in Thomas slag 50 parts increase is noted, the conclusion might be drawn that the same amount of soluble phosphoric acid had caused the production of twice as much plant substance as a like amount of phosphoric acid in the Thomas slag. In drawing such a conclusion one assumes that the entire phosphoric acid taken up by the plant had been turned to account in producing plant growth. This might not be the case. An estimation of the phosphoric acid in the plants might show that while the plants fertilized with Thomas slag contained as much total phosphoric acid as those manured with dissolved boneblack, the Thomas slag phosphoric acid was not there during the earlier stages of growth, when phosphoric acid was in greatest demand, but being more slowly soluble was taken up so late that it could not be worked over into plant substance. Now, it is the object of scientific experiments of this kind to carefully observe such conditions, and in order to do this it becomes necessary not only that the amount of plant substance produced be noted, but also that the absolute quantity of the specific fertilizing ingredient under consideration be determined. APPARATUS AND METHOD EMPLOYED IN THE ESTIMATION OF DRY MATTER. In order to make the numerous dry matter determinations in the substances harvested from the pots and cylinders the following apparatus is used: (1) Open cylinders are constructed out of tin, zinc, or copper 23 cm. long and 6 cm. in diameter. These cylinders decrease in size toward each end, so that they can be closed with rubber stoppers. Near the opening at the lower end is soldered a fine wire gauze, which allows a free circulation of air during the drying and at the same time prevents the material from falling out. (2) A large copper drying closet or box is made 1 meter long, 45 cm. broad, and 30 cm. deep. Into this copper box are set vertically 40 copper tubes, open at both ends, into which the cylinders above described exactly fit. Copper pipes for conducting steam surround the copper tubes. To prevent a loss of heat, the box is covered with felt. By the aid of such an arrangement the dry matter determinations are very rapidly made. Seeds are brought directly into these cylinders without being previously crushed or ground, and at the end of 20 hours a constant weight is obtained. The cylinders are then removed from the drying oven, both ends closed with rubber stoppers, and weighed after cooling. Straw and similar material is first put through a small cutting machine. Four hours is sufficient to dry such substances. After weighing if the substance is to be further examined it is ground fine in an Excelsior mill, and another dry matter determination made by placing a few grams in a drying bottle and heating to constant weight in an ordinary jacketed drying oven. RECENT WORK IN AGRICULTURAL SCIENCE. CHEMISTRY. Simplified method for the estimation of phosphoric acid by means of molybdate solution, J. HANAMANN (Chem. Ztg., 19 (1895), No. 25, pp. 553, 554).—The author suggests a modification of the molybdate method, by which he has obtained accurate results. The molybdate solution contains 100 gm. of molybdic acid to 1 liter of 10 per cent ammonia and 1.5 liters of nitric acid (sp. gr., 1.246). The yellow precipitate is obtained in the cold, frequently stirring the solution during a half hour. The dried precipitate, previously washed with ammonium nitrate and nitric acid, is brought to a dull glow in a platinum crucible. When a blue-black color is obtained the precipitate has a constant composition, containing 4.018 per cent of phosphoric acid. The author has found that the weight of the ignited precipitate varied from 35.2325 gm. to 35.2010 gm., according as its color was orange or a uniform blue black.-J. P. STREET. Metaphosphoric acid and the analysis of superphosphates, D. CRISPO (Rev. Chim. analyt. appliq., 3 (1895), p. 56; abs. in Chem. Ztg., 19 (1895), No. 28, Repert., p. 101). The author finds that in drying the superphosphate over the free flame the orthophosphoric acid undergoes a partial conversion into the meta acid, the extent of change varying from 10 to 90 per cent, according to the temperature. If the citrate method is used only the ortho acid is determined; with the molybdate method the total acid is obtained. Inasmuch as the fertilizing value of the meta acid has not yet been fixed, and as in the author's opinion superphosphate containing meta acid is of minor importance, he holds that both acids should be determined.-J. P. STREET. Some conditions affecting the accuracy of the determination of potash as potassium platinichlorid, A. L. WINTON (Jour. Amer. Chem. Soc., 17 (1895), No. 6, pp. 453-466).—The author states that the accuracy of the method of determining potash by precipitating the concentrated solution with platinic chlorid and drying the double salt at 130° C. depends on the compensation of three errors, due (1) to the solubility of the double salt in 80 per cent alcohol, (2) to the presence of water in the crystals which is not driven off at 1302, and (3) to the use of a factor based on the wrong atomic weight of platinum. "The solubility in alcohol occasions an error that can hardly be avoided. It could be diminished by using 95 per cent alcohol, but further experiments would be necessary to ascertain if this were best. "[The author's results show that] the error occasioned by the presence of water can be greatly reduced and the process of drying simplified by adding the platinum solution to a dilute solution of the potash salt (1 part of potassium chlorid, or six-tenths part potassium oxid to 100 cc. of water) and drying the potassium platinichlorid at 100° C. . . . "The factors, based on the atomic weights, as revised by F. W. Clarke up to January 1, 1894, would be 0.30688 for potassium chlorid and 0.1939 for potassium oxid." The kind of dish used, the temperature of the evaporation, the pres ence of free hydrochloric and sulphuric acids, did not appear to affect the results.-J. P. STREET. Determination of nitrogen in feeding stuffs by the Kjeldahl method, A. BÖMER (Chem. Ztg., 19 (1895), No. 9, pp. 166, 167).-The investigations of the author have shown that in order to get the full percentage of nitrogen in concentrated feeding stuffs, such as cottonseed meal, linseed meal, etc., by the Kjeldahl method, using simply sulphuric acid, it is necessary to continue the digestion longer than is usually done. Other investigators, namely, Gerlach and Süvern,' and O. Kellner, O. Böttcher, and G. Diesselhorst have made the same observations. Tests on cotton-seed meal and linseed meal, in which the digestion with sulphuric acid alone was continued for 4, 6, 10, and 16 hours, are reported, showing that the full percentage of nitrogen was obtained only after 10 hours' digestion. Tests on linseed meal, cottonseed meal, peanut meal, and rape cake, in which the feeding stuff's were digested with sulphuric acid containing phosphoric acid, with the addition of mercury, for 4, 6, and 10 hours showed that the full percentage of nitrogen was obtained in from 4 to 6 hours' digestion. Improved methods of water analysis, I. A. BACHMAN (Jour. Amer. Chem. Soc., 17 (1895), No. 4, pp. 296–303).-The author finds by experience with the Wanklyn process, as ordinarily carried out with the usual apparatus, that the losses by imperfect condensation, by the crude way of adding the permanganate solutions, and by the open air contamination of the distillate, render the results very inaccurate. He believes a rate of condensation exceeding 50 cc. in 15 minutes to be accompanied with loss. The proposition of Mallet to keep the original volume of liquid in the retort constant by the addition of ammoniafree distilled water is objectionable because of the difficulty of obtaining a large quantity of water of such purity. He finds that very much better results are obtained by the action of the full strength of the permanganate solution on a smaller and limited quantity of water and supplying the water under examination at about the rate of distillation. He describes the apparatus used and the method of procedure. 1 Chem. Ztg., 18 (1894), p. 1902 (E. S. R., 6, p. 864). The Kjeldahl process has been so modified by the author as to secure with the above apparatus gratifying results with the most obstinate organic compounds.-R. H. LOUGHRIDGE. The composition of maple sap, F. W. MORSE and A. H. WOOD (New Hampshire Sta. Bul. 25, pp. 4-9).-Maple trees with many branches and fully exposed to the sun afforded the richest sap; those in a thick grove the poorest. The sucrose in the sap from different trees ranged from 1.30 to 5.60 per cent. "The amount of sugar in the sap has not depended upon variety of maple, since soft maples have yielded both as high percentages of sugar, and as low, as rock maples." Toward the close of the season the sap was poorer than at the beginning of the season. Analyses revealed neither wide nor constant variation in the composition of the sap from different sides of the tree. The effect on composition of tapping by means of deep and shallow holes was investigated with inconclusive results. A drying oven, F. W. MORSE (New Hampshire Sta. Rpt. 1893, pp. 150, 151, fig. 1).—This oven, designed for drying substances in hydrogen at the temperature of boiling water, is described as follows: "It consists of a cylindrical copper box, with double bottom and wall. The inside of the oven is 7 in. in diameter and 9 in. in depth. The space between the walls is 1 in. It is fitted with a water gauge and a steam outlet. This outlet is a screw nipple, and may be coupled to a condenser if desired. The hydrogen enters the oven by means of a brass tube, which is coiled in the space between the bottom and wall and enters the inner oven near the top. The gas is thus thoroughly heated before entering the drying compartment. The gas passes out of the oven near the bottom. . . . The oven is made gastight by a mercury seal. A copper trough is fitted around the top of the oven a little below the rim. The trough is 14 in. in depth and in. in width, and is made with brass joints and coated on the inside with lacquer. The cover fits loosely in the trough, and the mercury makes a perfectly tight joint. Drying is hastened by placing an acid dish containing concentrated sulphuric acid on the bottom of the oven. A rack rests upon the acid dish to receive the watch glasses or drying flasks. In addition to heating the gas the oven is made more efficient by blackening the inner walls to increase radiation, and lining the under side of the cover with a thick sheet of asbestos. The outside of the cover is plated with nickel, which diminishes radiation outward. Repeated trials with a standard thermometer inserted in the oven at the top and between the walls have shown a difference of only two-tenths of a degree between the boiling water and the drying compartment." Classification of the chemical elements, L. DE BOISBAUDRAU (Compt. Rend., 120 (1895), No. 20, pp. 1097–1103). Argon, Lord RAYLEIGH (Nature, 52 (1895), No. 1337, pp. 159-164; Science, n. s., 1 (1895), No. 26, pp. 701-712).—A lecture delivered April 5, 1895, at the Royal Institution. Argon and helium, W. RAMSAY (Compt. Rend., 120 (1895), No. 19, pp. 1049, 1050). On calcium carbid and acetylene, BEHRENDS (Ztschr. angew. Chem., 1895, No. 11, pp. 338, 339). A furfurol derivative from levulose, J. KIERMAYER (Chem. Ztg., 19 (1895), No. 43, pp. 1003-1005). Determination of glycogen in hay and in muscles, KESTJAKOWSKY (Pharm. Ztschr. Russland, 34 (1895), p. 25; abs. in Jour. Pharm. et Chim., ser. 6, 15 (1895), No. 12, p. 613) |