In Tables 2 and 3 additional results of collaborators working upon special mixtures and raw materials are reported. TABLE 2. Comparative results of potash determination expressed as potassium oxid. TABLE 3. A comparison of the official and modified official methods for potash. The following is a summary of the cooperative work since 1914, investigating the effect of adding hydrochloric acid to the potash solution. YEAR TABLE 4. Cooperative results from 1914 to 1917, expressed as potassium oxid. DESCRIPTION OF SAMPLE WITH HYDROCHLORIC ACID OMITTED per cent per cent The cooperative results during the past four years on samples of many different mixtures have shown that no difference is caused by the addition or non-addition of hydrochloric acid to the potash solution. In view of the data here reported, the referee concludes that the addition of 2 cc. of concentrated hydrochloric acid to the water extract of mixed fertilizers and boiling is an unnecessary operation, that its elimination is a desirable simplification and may be effected without sacrifice to accuracy. PERCHLORATE METHOD. The following is a summary of the results reported by collaborators, using the perchlorate and official methods: The results which are presented in the table indicate that the perchlorate method is not as satisfactory as could be desired, yet there appears to be an improvement over the results obtained by collaborators in former years. Several chemists obtained excellent results by this method in comparison with the official method. In the determination of potash by the perchlorate method it is extremely important that the details of manipulation be followed closely, and it is believed that the method of procedure, as given in the directions to collaborators, will give reasonable accuracy. Progress with this method has been relatively slow for the reason that collaboration from chemists experienced with the method has been difficult to obtain. So it seems reasonable to assume that the relatively wide differences in the results reported by several analysts may be attributed in a large measure to their inexperience with the method. RECOMMENDATIONS. It is recommended (1) That the official method for the preparation of potash solution1 be revised to read as follows: Place 2.5 grams of the sample upon a 12.5 cm. filter paper and wash with successive portions of boiling water into a 250 cc. graduated flask until the filtrate amounts to about 200 cc. Add to the hot solution a slight excess of ammonium hydroxid and sufficient ammonium oxalate to precipitate all the lime present, cool, dilute to 250 cc. mix, and pass through a dry filter. (2) That the work on the availability of potash be continued. (3) That the study of the perchlorate method be continued. A MODIFIED METHOD FOR THE DETERMINATION OF WATER-SOLUBLE POTASH IN WOOD ASHES AND TREATER DUST. By H. D. HASKINS (Agricultural Experiment Station, Amherst, Mass.). It is a well established fact that products such as wood ashes, treater dust, or so-called lime-potash, manure ashes, etc., contain a much higher percentage of potash soluble in hydrochloric acid (strength 1 to 1), as well as weaker acid solutions (N/5 hydrochloric acid), than is dissolved by boiling water. It is conceivable that at least a portion of this water-insoluble potash may be loosely held in combination with silica as basic silicates, resulting from the process under which the wood ashes and treater dust are made. The presence of more or less of these basic silicates was recognized 1 Assoc. Official Agr. Chemists, Methods, 1916, 12. by the earlier manufacturers of potash, who established the custom of allowing the ashes to remain in contact with water for a few days before subjecting them to the final leaching with hot water. Ashes thus treated usually gave a larger yield of potash than when leached without the soaking process. Water-soluble potash was determined in a number of samples by the official method. Water-soluble potash was also determined by allowing the ashes to remain for two days in contact with just enough water to cover the ashes contained in a 4-ounce beaker. Subsequently, the ashes were washed with successive portions of boiling water to a volume of 200 cc. and, from this point, the manipulation was according to the official method. One sample of treater dust and 21 samples of ashes were analyzed by the two methods, the acid-soluble potash being determined in each case. The results are given in the following table: This study indicates that freshly made dry ashes and dry treater dust, or cement potash, will yield appreciably more water-soluble potash if allowed to remain in contact with water for several hours previous to extracting with boiling water. In the case of ash products which contain considerable water (12 to 30 per cent), very little advantage results from the preliminary treatment with water. It would seem |