AGRICULTURAL, CHEMISTRY AGROTECHNY. 513 



to evaporate off the alcohol. After the danger from frothing has ceased put 

 on full heat until completion, and place on a hot plate covered with a sheet of 

 asbestos (temperature from 130° to 160° C), raise the temperature, and boil 

 off the sulphuric acid. Then place in a cold muffle, heat gradually to expel 

 volatile products, and finally burn the carbon avpay. After cooling, cover the 

 residue with water and allow to stand for a few minutes. Then transfer the 

 contents of the crucible by scraping with a spatula and washing, into a 600 

 cc. beaker, and add slowly 40 cc. of a 1 : 1 sulphuric acid. To the crucible add 

 10 cc. of dilute sulphuric acid, scrape, and wash the contents into the beaker. 

 When the reaction is over, add to the solution 30 cc. of nitric acid (specific 

 gravity 1.42) and 50 cc. of sulphuric acid (specific gravity 1.84), cover and boil 

 briskly on a hot plate until fumes of sulphuric acid are given off, and allow to 

 fume for 10 minutes. After this cool but do not allow to solidify, pass the stem 

 of a funnel bent at an angle over the lip of the beaker, which is covered, and 

 add successively small amounts of water from the wash bottle until violent 

 action has ceased, then rapidly 150 to 200 cc. of water, and remove the funnel 

 and watch glass cover. Wash the contents of the beaker into a 1-liter Erlen- 

 meyer flask, cool, pass in hydrogen sulphid for a few seconds, and add am- 

 monium hydroxid (28 per cent), rotating until the black color of the precipitate 

 persists. Immediately make acid with 1 : 1 sulphuric acid, and add 10 cc. excess 

 of dilute acid. Then dilute to 1 liter with boiling water and continue passing 

 hydrogen sulphid rapidly for 25 minutes more, stopper, and allow to stand over 

 night. 



After this period heat on the steam bath for ^ hour, rotating 2 or 3 times 

 during the interval, cool partly, filter on a 12.5 cm. filter, and wash 6 times, 

 filling the filter each time with a solution consisting of 50 cc. of glacial acetic 

 acid and 100 cc. of a saturated solution of ammonium acetate made up to 1 liter 

 with water. Finally, return the precipitate and filter to the original Erleu- 

 meyer fiask, add 100 cc. of 20 per cent potassium hydroxid solution, boil over 

 a free flame for a couple of minutes until the solution is clear and the paper 

 disintegrated, decant into a 400 cc. beaker and through a double 12.5 cm. filter 

 paper, and wash the flask and filter with hot water successively until the 

 filtrate comes through colorless. After this add 20 cc. of concentrated hydro- 

 chloric acid, a few drops of phenolphthalein, then hydrochloric acid until the 

 color of the solution disappears, and finally 1 cc. more of the acid. Test with 

 litmus paper, place the solution on a steam bath for 20 minutes, and cover. 



The next morning, if the solution is not acid make it so with hydrochloric 

 acid, and then add 1 cc. in excess of this. If the supernatant fluid is acid and 

 turbid then make it alkaline with potassium hydrate and bring it back to 

 acidity with acid and add 1 cc. in excess. Heat on the steam bath for i hour, 

 stirring 2 or 3 times during the interval, and then filter through a 12.5 cm. 

 filter. The filtrate must be perfectly clear. Wash the precipitate alternately 

 with distilled water and ammonium acetate solution until free from chlorids, 

 then place it with the filter in a porcelain crucible, dry, char on asbestos gauze, 

 burn, and weigh as stannic oxid. 



The author points out that no necessity exists for weighing the tin in the 

 metallic state. Comparative results obtained, with this method and Schryver's 

 with vegetables, fruit, and fish are given and show a satisfactory agreement. 



Salicylic acid reactions, C. Reichard (Pharm. Zentralhalle, 51 {1910), No. 

 33, pp. 743-71/9). — A general discussion in regard to salicylic acid and its re- 

 actions. 



The determination of lactose by the copper methods, L. Bourdet {Bui. 

 Sci. Pharmacol., 17 {1910), No. 1, pp. 16-19). — A discussion of the value and 



