There is a method, known as Prof. KOKETSU's "Pulvermethode," which is recognized as a rational way to determine and compare the content of matter or the degree of physiolosical functions in plants or organisms. When, however, the material to be pulverized was extremely fibrous or pubescent, investigators have heretofore encountered difficulty in adopting the above mentioned method. This paper proposes a way of overcoming this difficulty, namely, by the application of liquid air (or O2). The dried material to be used, which can, if necessary, be fresh, is placed in a mortar. Liquid air is poured in; and the material, thereby thoroughly frozen and thus made brittle, is then readily ground with a pestle as usual. In order to test the efficiency of this method of milling with liquid air, as compared with the ordinary way of milling without liquid air, a study has been made, of which the principale results are as follows: 1) The time required to grind any given material was much less. How much less, depends on the nature of the material used. The time required was from 6% to 72%, and on the average was about 40% of the time used in milling by the ordinary method. 2) The loss of material was much less, in the case of pulverizing fibrous or pubescent material, which by the other method is a lengthy process. In pulverizing ordinary materials, there was no particular difference seen in this respect. 3) The specific powder gravity of any given material was about the same as that prepared by the other method. In short, from each of the results obtained, it was clearly shown that the method of milling with liquid air gives good results. Therefore, by using it as a supplementary method when pulverizing fibrous or pubescent material, the difficulty in question is overcome.
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