33? 



M. TSUKAMOTO. 



Commercial Kaki-shibu even in high dilution gives precipi- 

 tates with basic lead acetate, mercuric chloride, mercuric nitrate 

 and copper acetate. Since dilute phosphotungstic acid yields 

 no precipitate, proteins seem to be absent to a notable degree. 1 



One of the most striking properties of the Kaki-shibu is the 

 production of an insoluble film on evaporation to dryness. 

 Whether this film is exactly the same as the film formed on the 

 surface of the liquid on long exposure to the air may be doubted, 

 since there evidently takes place a considerable oxidation in 

 the latter case. In the former case, however, the loss of 

 solubility in water is only due to the loss of the greater part of 

 the acid by volatilization. 2 Furthermore, these two films show 

 the following differences in their behaviour : The former film 

 swells somewhat when moistened, and is very easily broken. 

 The latter film is elastic and more coherent. When treated with 

 dilute acetic acid the former first swells up and gradually 

 dissolves on standing, but the latter is almost insoluble and 

 shows no perceptible change after long standing. On addition 

 of concentrated sulphuric acid the former dissolves at once, while 

 the latter only very slowly. On boiling with dilute nitric acid t 

 the former dissolves very easily giving a fine yellow solution, 

 but the latter is dissolved only with difficulty. When boiled 

 with caustic potash the former dissolves also much more easily 

 than the latter. In order to determine the quantity of the film 

 formed by evaporation, 10 c.c. of Kaki-shibu was evaporated to 

 dryness and this residue was treated repeatedly with cold water 

 until no acid reaction could be percieved in the washing. The 

 insoluble film was dried and weighed, giving 0.351 g. or 3.420% 

 for a sample of the new Kaki-shibu and 0.360 g. or 3.51 2% for a 

 sample of the old ; 3 they contained respectively 0.349 g. or 99-5% 



1 In the new Kaki-shibu a little turbidity is observed by phosphotungstic acid. 



1 Fresh juice is not a homogeneous solution but contains much fine suspended 

 matter. This gradually goes in solution as the amount of acid is increased by bacterial 

 action, since the suspended matter of the fresh juice gives a much stronger tannin reaction 

 than the filtered liquid does. 



8 It appears that the film formed on evaporation from the new Kaki-shibu is more 

 soluble than that of the old juice. 



