Studies on the Histological Change of the Calf-skin suring the Process (II)

VI. Changes of amino acid in the calf skin by liming The changes of amino acid both in the calf skin and lime solution, in the process of liming were examined chiefly by paper chromatography. The results were as follows: 1) Amino acids, detected in the calf skin at the early stage of liming were of sixteen kinds, such as glycine, alanine, valine, leucine, serine, phenylalanine, cystine, tyrosine, histidine, threonine, arginine lysine, asparatic acid, glutamic acid, proline, and oxyproline. Three of these amino acid, cystine, threonine and histidine, vanished after 10 or 15 days of liming, while thirteen other amino acids were detected even after the skin had been soaked for 20 days. 2) By liming some sorts of amino acid of the calf skin were dissolved in lime solution. Most of these amino acids construct soluble portion, such as albumines, globuline, mucoid and so on. Most of them are presumed to have been dissolved in lime solution by 10th day or so after soaking in lime solution, considering the rise and fall of the quantity of volatile ammonia in lime solution, and the kind of amino acids soluble in lime solution. 3) Insoluble protein in the skin is also being resolved gradually by saturated lime solution, and it is considered that the diesoluble ammount of amino acid should increase if it was soaked in lime solution for a long time. That is to say, the chief amino acid composing collagen, lysine, arginine, proline and oxyproline were surely detected after the skin was soaked for about 20 days. 4) Gelatin can be obtained by heating collagen fibre with water. In this case most important point to make fine quality of gelatin is that the collagen, not yet resolved and as pure as possible, should be used as materials. Considering this experiment and results written in the preceding chapters, it is deducted that the skin should be soaked in lime solution for about 20 days at 18C for the purpose of making gelatin from calf skin. VII. Studies on the relation between the period of liming and the quality of leather and gelatin In order to investigate the relation between the period of liming and the quality of leather and gelatin, the calf skin was soaked in the saturated lime solution at 183C, and the leather and gelatin were made one after another. 1) The calf skin was tanned rather well after it was soaked in lime solution for 6 or 10 days. The best quality leather was that which remained in the lime solution for 8 days. The tention strength and the section of this leather were best. 2) Gelatin made from the calf skin after it had been sosked for 20 days in lime solution, was the best in quality. The suitable period of liming of calf skin to make gelatin is from 17 to 23 days at 18℃. 3) As the results of this research, it proved, what the writer mensioned in the preceding chapters, not to be mistaken.