Before drying a sample it is necessary to take into consideration whether or not the product will be modified by desiccation as would be the case, for instance, with superphosphates. With these, which are often in a state more or less agglomerated, it is recommended to introduce into them, in order to divide them, a certain quantity of calcium sulfate in order to obtain them in a pulverulent state. In the case of animal débris they should be divided as finely as possible with the aid of scissors and then passed through a drug mill if dry enough. They are then mixed by hand and may finally be obtained in a state of considerable homogeneity. When fertilizers are in a pasty state more or less liquid, they are dried at 100°, first introducing a little oxalic acid in case they contain any volatile ammoniacal compounds. The product of desiccation is then passed through a mill. Before treating in this way it is necessary to be sure that the composition will not be altered by drying. In the case of a mixture containing superphosphates and nitrate, for instance, drying would eliminate the nitric acid. In such a case the free phosphoric acid should be neutralized with a base like lime. In the case of fertilizers containing both nitrates and volatile ammoniacal compounds the addition of oxalic acid might also set free nitric acid during the desiccation. In such a case it is necessary to dry two samples; one with the addition of oxalic acid for the purpose of estimating the ammonia, and the other without the acid for the purpose of estimating the nitrate. A qualitative analysis should precede all the operations so as to determine the nature of the material to be operated on. =14. German Method.=—In the method pursued by the German experiment stations it is directed:[8] (1) Dry samples of fertilizers must be passed through a sieve and afterwards well mixed. (2) With moist fertilizers, which can not be subjected to the above process, the preparation should consist in a careful and thorough mixing, without sieving. (3) On the arrival of the samples in the laboratory their weight should be determined. The half of the sample is prepared for analysis and the other part, to the amount of a kilo, should be placed in a glass vessel, closed air-tight, and placed in a cool place for at least a quarter of a year from the time of its reception, in order that it may be subjected to any subsequent investigations which may be demanded. (4) In the case of raw phosphates and bone-black the amount of water which they contain should be determined at from 105° to 110°. Samples which in drying lose ammonia in any way, should have this ammonia determined. (5) Samples which are sent to other laboratories for control analyses, should be sent securely packed in air-tight glass bottles. (6) The weight of the samples sent should be entered in the certificates of analysis.