B. W. Bull on Emulsine and its Composition. 77 



The use of a few precautions has enabled me to obtain emulsine 

 perfectly white and consequently differing in appearance entirely 

 from that described by Robiquet and Ortloff, who both agree in 

 ascribing to it the color mentioned above. 



If the freshly precipitated substance is at first washed out with 

 strong alcohol till all soluble matter is removed, afterwards with 

 absolute alcohol till deprived of every trace of water, and at last 

 dried upon glass in vacuo over sulphuric acid, it is obtained in 

 snow-white brittle masses, entirely opaque, without lustre and 

 breaking with a dull starchy fracture. It is also more soluble 

 than that prepared in the ordinary manner as at first described. 

 I have not succeeded in all cases in obtaining a white preparation, 

 and have found by experience that the following are requisite 

 for success. It should be prepared in small quantities in order 

 that it may dry as rapidly as possible. The powder remain- 

 ing after pressure of from one to two pounds of the kernels, is a 

 suitable amount to operate upon. From one pound of the ker- 

 nels I have generally obtained six grammes emulsine, and this 

 quantity can be conveniently dried under one receiver of ordi- 

 nary size. 



It should previously be freed as much as possible from alcohol 

 by pressure between unsized paper, and afterwards placed under 

 the receiver in glass or porcelain vessels, (watch-glasses answer 

 the purpose very well,) in layers of not more than one or two 

 lines in thickness : if thicker, or if from other causes it is not dried 

 by the expiration of twelve hours, it assumes a more or less yel- 

 low or reddish tinge. If large quantities are taken, the time 

 requisite for filtering and washing is unavoidably prolonged, and 

 a preparation more or less colored is the result. When dried over 

 sulphuric acid, in a receiver from which the air has not been ex- 

 hausted, but after having in other respects been treated as above 

 last mentioned, it appears to absorb moisture even then, and be- 

 comes upon drying, gum-like transparent and yellow. Still it 

 does not seem to form any definite combination with water, for a 

 portion of this gummy transparent variety upon being reduced to 

 powder and dried over sulphuric acid till a constant weight was 

 obtained, did not suffer any farther diminution in weight by ex- 

 posure to a temperature of 100° C. 



If dark colored emulsine is redissolved in water, separated by 

 filtration from the insoluble portion and re-precipitated by alcohol 

 *ith subsequent drying in vacuo, it becomes snow-white even if 

 not treated with absolute alcohol. 



It is generally more or less transparent however, and preserves 

 a glossy lustre externally. But this is not an economical method 

 of obtaining it, as a large amount of the substance employed re- 

 gains undissolved. Both the white and colored emulsine possess 

 "s characteristic property of decomposing amygdaline in the high- 



