1881.] 



Letter by Br. W. Roberts. 



147 



The vortex which first passes through the point of intersection of 

 the direction of motion of the vortices is deflected towards the direc- 

 tion of motion of the other, it increases in radius and energy, and its 

 velocity of translation is diminished ; the other vortex is deflected in 

 the same direction, it diminishes in radius and energy, and its velocity 

 of translation is increased. 



XL Letter addressed to the Secretary R.S. by Dr. W. Roberts, 

 F.KS. Received December 1, 1881. 



In deference to the request of Mr. W. R. Dunstan, I wish to correct 

 an error of omission in my paper " On the Estimation of the Anx- 

 iolytic and Proteolytic Activity of Pancreatic Extracts," printed in 

 "Proc. Roy. Soc," vol. 32, p. 145. 



Mr. Dunstan points out to me that I had overlooked a paper by 

 himself and Mr. A. F. Dimmock on the "Estimation of Diastase," 

 published in the "Pharmaceutical Journal" for March 8th, 1879, 

 wherein he described a process, in which (as in my method) the 

 cessation of the iodine reaction is utilised for the purpose of gauging 

 the activity of diastasic solutions on starch gelatine. 



I had not previously seen this paper, and am now glad to have the 

 opportunity of referring to it those who are interested in diastasi- 

 metry. 



