According to Crispo, the original Glaser method, with its various modifications, is not to be considered reliable, and the choice lies between the molybdic method as usually practiced, and his own for the accurate estimation of iron and alumina. Manganese disturbs the accuracy of the results unless the directions given are carefully followed. Manganese phosphate is soluble at all temperatures below fifty. If then the mixture of the phosphates be allowed to cool before filtering, the iron and aluminum salts are not contaminated with manganese. This method of Crispo is somewhat tedious, but it is claimed that these variations of the molybdic method render it exact in respect of the determination of iron and alumina. =38. Method Employed in Geological Survey.=—Chatard gives the following directions for conducting the Glaser-Jones process[28]: The distillation flask containing the alcoholic filtrate is connected with its condenser and heated on a water-bath until no more alcohol comes over. This distillate, if mixed with a little sodium carbonate and redistilled over quicklime, can be used over and over again, so that the expense for alcohol is really very slight, while in the use of the Glaser method, with its large amount of sulfuric acid, all the alcohol is lost. When the distillation is ended the residue in the flask is washed into a platinum dish and evaporated to a small bulk on the water-bath. The dark brown color produced is due to the presence of organic matter and this must be destroyed, as it prevents the complete precipitation of the phosphate in the subsequent operation. The organic matter is best destroyed by removing the dish from the bath, adding a small quantity of pure sodium nitrate, and heating very carefully over the naked flame, keeping the dish well covered with a watch-glass to avoid spattering. The mass fuses to a colorless, viscous liquid, becoming glassy when cooled and is readily soluble in a hot very dilute solution of nitric acid. The solution transferred to a beaker is made distinctly alkaline with ammonia and carefully neutralized with acetic acid, diluted with hot water, boiled, and the precipitate allowed to settle, after which it is separated by filtration. After the precipitate has been completely transferred to the filter, the washing is completed with a dilute solution of ammonium nitrate. The precipitate is dried, ignited, cooled, and weighed. The determinations should be made in pairs, one portion being used for the estimation of the phosphoric acid by fusing with a little sodium carbonate, and the other, after fusion with sodium carbonate, is dissolved with sulfuric acid and the iron reduced and titrated with potassium permanganate solution. The filtrate from the iron and alumina determination is evaporated to a small bulk, made strongly ammoniacal and allowed to stand for some time when the magnesia present separates as ammonium magnesium phosphate which is determined in the usual way.