A consideration of the figures given above, would seem to justify the change made in the Regulations at the beginning of the last season, in abolishing the twenty-five (25) per cent. margin previously allowed in branding the guaranteed analysis on the bags and replacing this with the minimum guaranteed analysis only. The Regulations allowing the twenty-five (25) per cent, margin were not issued till December 12th, 1881-so late as to have but little effect on the trade of the season of 1881-82; but as no changes were made in these Regulations in the following season of 1882-83, their full effect was felt. The Regulations of last season (1883-84) abolishing the twenty five (25) per cent. margin were issued in time to meet with compliance from nearly all the manufacturers, and the full effect of the change may be claimed to have been felt. Now, an examination of the figures in the above tables will show that the average analyses fell off during the season of 1882-83, while the full effect of the twenty-five per cent. margin was felt, but during the last season (1883-84) reached a higher point even than in 1881-82. In comparing the commercial values given in the above tables, care must be taken not to overlook the fact that there has been a steady diminution in the commercial values assigned in successive seasons to the different fertilizer ingredients. After 15 minutes add 30 c.c. of ammonia solution of density 0.96. Let stand several hours. (Two hours are usually enough.) Filter; wash with dilute ammonia; ignite intensely for ten minutes and weigh. 5. CITRATE-SOLUBLE PHOSPHORIC ACID.-The sum of the watersoluble and citrate-insoluble substracted from the total gives the citratesoluble. PREPARATION OF REAGENTS. 1. TO PREPARE AMMONIUM CITRATE SOLUTION.-Mix 370 grams of commercial citric acid with 1500 c.c. of water; nearly neutralize with crushed commercial carbonate of ammonia 410 grams; heat to expel the carbonic acid; cool; add ammonia until exactly neutral (testing for excess both of acid and alkali by aid of delicate red and blue litmus papers), and bring to volume of two liters. Dilute further until the density is 1.09 as tested by the balance or accurate specific gravity spindle. 2. TO PREPARE SOLUTION OF MAGNESIUM NITRATE.-Dissolve 320 grams of "calcined magnesia " in nitric acid, avoiding excess of the latter; then add a little "calcined magnesia " in excess and boil; filter from the excess of magnesia, ferric oxide, &c., and bring to volume of two liters. 3. TO PREPARE MOLYBDIC SOLUTION.-Dissolve 100 grams of molybdic acid in 400 grams, or 417 c.c. of ammonia of sp. gr. 0.96, and pour the solution thus obtained into 1500 grams or 1250 c.c. of nitric acid of sp. gr. 1.20. Keep the mixture in a warm place for several days, or until a portion heated to 40°C. deposits no yellow precipitate of ammonium phospho-molybdate. Decant the solution from any sediment, and preserve in glass-stopped vessels. 4. TO PREPARE AMMONIUM NITRATE SOLUTION.-Dissolve 200 grams of commercial ammonium nitrate in water and bring to a volume of two liters. 5. TO PREPARE MAGNESIA MIXTURE.-Dissolve 22 grams of recently ignited "calcined magnesia " in dilute hydrochloric acid, avoiding excess of the latter. Add a little " calcined magnesia" in excess and boil a few minutes to precipitate iron, alumina and phosphoric acid; filter; add 280 grams of ammonium chloride, 700 c.c. of ammonia of sp. gr. 0.96 and water enough to make the volume of two liters. Instead of the solution of 22 grams of "calcined magnesia," 110 grams of crystallized magnesium chloride (MgCl2. 6H2O.) may be used. 6. DILUTE AMMONIA FOR WASHING.-One volume ammonia of sp. gr. 0.96 mixed with three volumes of water, or, usually, one volume of concentrated ammonia with 6 volumes of water. SEPARATION AND DETERMINATION OF POTASH IN COMMERCIAL FER TILIZERS. Boil 10 grams of the fertilizer with 5 c.c. strong hydrochloric acid and 300-400 c.c. of water for ten minutes. Cool the solution, and, without filtering, make it up to 1000 c.c.; mix thoroughly, and filter through a dry filter. Take an aliquot corresponding to 0.5 or 1.0 gram, dilute if necessary to about 150 c.c. heat to boiling, and precipitate the sulphuric acid with a slight excess of barium chloride solution. Without filtering add an excess of barium hydroxide, and heat again to boiling. Filter and wash, at first by decantation, till the washings are free from chlorides. Heat the filtrate nearly to boiling and precipitate the barium salts with ammonium carbonate and a little ammonia solution. Filter and wash ; evaporate filtrate and washings to dryness, and ignite below a red heat till the ammonium salts are removed and the organic matter is oxidized as completely as possible. The residue, consisting of chlorides of potassium, and sodium, with some charcoal and possibly a little barium salt which escaped precipitation, is digested with hot water; a few drops of ammonium carbonate are added, and the solution filtered and washed. The filtrate and washings are again evaporated to dryness and ignited gently. The mixed chlorides are dissolved in water, an amount of platinum tetra-chloride solution is added more than sufficient to form the double salt with all the potash and soda present, and the solution is evaporated at or below 100°C. so nearly to dryness that it becomes solid on cooling. To the cold mass 10-20 c.c. of strong alcohol (80 p. c.-95 p. c.) are added and the mass is well broken up with a stirring rod or pestle. After standing 5-10 minutes the supernatant liquid, which must have a reddish color from excess of platinum tetra-chloride, is poured on a filter; more alcohol is added to the mixture of the double salts, and the whole stirred and pulverized and washed by decantation until the washings are perfectly colorless. The precipitate is then brought on the filter by means of a wash bottle containing alcohol. The salt is dried at 100°C. and weighed. After weighing, the salt is dissolved from the filter with hot water and the filter is dried and weighed together with any platinum which may have been reduced in drying down the solution with platinum tetrachloride, or other impurities. The actual potash is reckoned from the weight of the double chloride of potassium and platinum by multiplying by 0.19308. Potassium chloride is reckoned from the double salt by multiplying by 0.3056. These factors are based on the following atomic weights: |