THE BY CHARLES B. DAVIS. Received February 3, 1902. HE apparatus (Fig. 1) may be described as follows: A (Fig. 2, I) is the water or acid chamber of about IO CC. capacity, to the bottom of which is attached a bent capillary tube for the passage of the water or acid to the body of the apparatus. The liquid in this chamber is held in place by virtue of the existing pressure below and partial vacuum above the liquid, there being no stop-cocks to get out of order. B is the drying chamber which is supplied with two bent capillary tubes for the introduction of the gas into the drying material, which is generally concentrated sulphuric acid. Both chambers are supplied with glass stoppers, and are separated by a glass partition. C (Fig. 2, II) is the body of the alkalimeter having a capacity of about 75 cc., which is intended to carry the material to be tested. The convenience of this section of the apparatus is that it may be tared on the balance, and a portion of the sample to be examined weighed directly into the alkalimeter, thus avoiding all loss caused by transferring, as in the average alkalimeter now in use. I and II are connected by an air-tight ground joint. The alkalimeter having been thoroughly cleansed and dried, the body of the apparatus is tared, and a portion of the material to be examined, in powdered form (which should contain not more than 0.5 gram of carbonate), is weighed in together with 2 grams of a mixture of equal parts salicylic and benzoic acids. The mixed acids I have found to give better results for all carbonates, than either alone, although either will answer the purpose in most cases. The drying chamber is half filled with concentrated sulphuric acid, and to the water chamber is added 10 cc. distilled water freed of the gases it usually contains. Both sections are now brought together and allowed to attain the temperature of the balance. The alkalimeter thus charged is carefully tared, and by removing both stoppers the water flows into the body of the apparatus, which causes an immediate generation of carbon dioxide; this moisture-laden gas passes through the capillary tubes into the acid of the drying chamber where it is deprived of its moisture and escapes. When this first evolution of gas ceases, the apparatus is carefully shaken, and this is repeated until no further generation of gas results. No heat is employed for the alkaline carbonates, while for the earthy carbonates a temperature as low as 55° will be found to be sufficient. The alkalimeter is now freed of its remaining carbon dioxide by causing 0.5 liter of dry air, freed from carbon dioxide, to pass through the apparatus. The following results were obtained with calcium, barium, and magnesium carbonates: This method for estimating carbon dioxide will be found useful in the examination of baking-powders, as well as for the alkaline and earthy carbonates. THE DETERMINATION OF LITHIA IN LEPIDOLITE. THE BY W. J. SCHIEFFELIN AND W. R. LAMAR. Received February 3, 1902. HE J. Lawrence Smith method for decomposing the silicate is more convenient than that of dissolving in hydrofluoric acid, as the alkalies are separated from the alumina as chlorides in one step, thus avoiding two precipitates, aluminum hydroxide and barium sulphate, which are sure to hold back lithia. A modification we have found advisable, is to remove the last traces of calcium by means of ammonium oxalate.' The Gooch method for separating lithia from the other alkalies gives the best results. A small direct vision spectroscope is an important aid in deciding when precipitates are thoroughly washed, etc., by examining a fraction of a drop held in a looped platinum wire. The decomposition is conducted in the usual way,' care being taken that the crucible is not heated too highly, as there is danger of loss of the lithium chloride, and also of the mass becoming vitrified and difficult to dissolve. The trituration must be thorough and the leaching complete or some lithia will be held back. (The residue when treated with hydrochloric acid should leave no undecomposed mineral.) After the dish containing the alkalies is dry, it is heated on an asbestos disk, or a triangle high above the flame, to drive off the ammonium chloride; this may take three-quarters of an hour; if it is done too rapidly, lithium chloride will go with it. Ten cc. of hot water and one drop of hydrochloric acid will dissolve the residue in the dish, and the addition of a few drops of ammonia, and 1 or 2 drops of ammonium oxalate precipitate the remaining calcium.* The chlorides of the alkalies are filtered into an Erlenmeyer flask, of thin glass (75 or 85 cc. capacity), which is placed in the air-bath, or on an asbestos disk over a small flame, and evaporated until the salts show signs of crystallizing (the solution will be down to 1 or 2 cc.); then a few drops of water are added, to effect solution, and 1 or 2 drops of concentrated hydrochloric acid to transform any hydroxide or oxychloride into chloride. Fifteen cc. of amyl alcohol (b. p. 129°-132° C.) are now added, and the flask is placed on an asbestos disk, which is slightly slanted so that the lower aqueous layer flows to one side, and the point of a Bunsen flame (1.5 inches high) is applied to the asbestos directly under the raised side of the flask. It is important to adopt this precaution as it allows the amyl alcohol to come to gentle boiling and continue boiling after all watery vapor 1 Hillebrand: Bull. U. S. Geol. Survey, No. 176. 2 U. S. Geol. Survey Bull. No. 42, p. 73; Am. Chem. J., 9, 33; Proc. Am. Acad., p. 177 (1886); Chem. News, 55, 18, 29, 40, 56, 78. 3 Fresenius, 140. + Hillebrand: U. S. Geol. Survey, Bull. No. 176. |