DETERMINATION OF I'llOSPHORIC OXIDE. 363 



this evaporation molybdic acid, together with impurities, is depo- 

 sited. The evaporation is best carried out in a large enamelled 

 iron dish, since the risk of breakage of a porcelain dish is very 

 great owing to the formation of a hard layer of molybdic acid on 

 the bottom of the dish. After the evaporation, the contents of 

 the dish, a very strongly acid solution, are allowed to cool. The 

 mother-liquor is then poured off, and the molybdic acid at the 

 bottom of the dish is washed once or twice with distilled water. 

 Strong ammonia solution is now poured into the dish, when the 

 molybdic acid will slowly dissolve, while iron, etc.. will remain 

 as a dark brown preci])itate. Since the ammonia is neutralised 

 by the molybdic acid, the solution should be kept alkaline by the 

 addition at intervals of strong ammonia solution. The precipitate 

 is filtered off, and the clear solution reduced in bulk by evapora- 

 tion. This solution is often coloured blue by lower oxides of 

 molybdenum. Prescott* oxidises these by the addition of hydro- 

 gen peroxide. We have found that during the evaporation the 

 blue colour disappears. Molybdic acid is precipitated from this 

 solution by the addition of strong nitric acid. The precipitate, con- 

 sisting of almost pure molybdic acid, is allowed to settle, filtered, 

 and washed with distilled water. The washing should not be 

 repeated too often, as the precipitate is somewhat soluble in water. 

 The precipitate on the filter paper is dissolved in strong ammo- 

 nium solution, and the solution evaporated, when crystals of 

 ammonium molybdatesettle out. The crystals are collected, and 

 dried in the steam oven until the strong smell of ammonia has 

 disappeared. The product obtained in this laboratory by the 

 above method contains about 85 per cent, of M0O3, and cor- 

 responds approximately to the formula (NH4)gMo. 0,4, HjO, while 

 the formula of the amnion itmi molybdate of commerce is usually 

 given as (NH4),.Mo,0,,, 4H,0. 



Chemical Laroratorv, 



Union Department of Agriculture, 

 Pretoria. 



Alligators as food.' — A. M. Reese gives an account 

 in Scicnce'f of a practical test in the use of alligator meat as 

 human food. The meat was parboiled, rolled in egg and cracker 

 crumbs, and fried. Thus prepared it was highly appreciated by 

 a group of some thirty persons who partook thereof. In the 

 Southern States of America, w^here alligator hides are prepared 

 for various commercial fancy purposes, it is suggested that this 

 meat, hitherto dealt with as refuse, be utilised for human food. 



* Loc. cit. ^^ ^.„^ 



t47 (1918), 6^0, 641. /^^'^>V 



