246 Influence of Colloids upon Crystalline Form, fyc. [June 19, 



'Experiment 10. — If a little albumin be added to the solution of urea 

 and if then to the filtered liquid the equal bulk of nitric acid be 

 added as rapidly as possible, the albumin is only partially precipitated, 

 and, after a little warming, is all re-dissolved. In the resulting clear 

 straw-coloured liquid there appear during cooling spherical bodies, 

 suddenly suspended at various depths. They look very much like 

 little globules of solidified fat, and grow rapidly from the size of a 

 mustard-seed to the bulk of a pea. Bach is composed of crystalline 

 fibres radiating from the centre, and whereas the deposit in the pre- 

 vious experiment does not occupy more than one-third of the fluid, 

 these fill the whole bulk of the fluid and, mutually compressing each 

 other, give the contents of the tube in which the experiment is made 

 the appearance of a bar of beautiful fibrous spar. The experiment 

 occurred to me first in the examination of concentrated albuminous 

 urine, but it succeeds equally well with pure solutions, and forms, I 

 submit, the most brilliant illustration of Mr. Rainey's valuable work 

 hitherto made known. 



DESCRIPTION OF PLATE 1. 



Figures 1 to 11. Cholesterin in albumin : 1, 2, on surface ; 3-11, successive stages 

 of forms observed in the cholesterin deposited within the substance of the 

 albumin. 



Figures 12 to 16. Cholesterin after being heated with acetic acid and glycerin : 12, 

 sphere first formed ; 13, sphere in act of contracting and exuding smaller 

 spheres and tubular processes ; 14, mass of globules like mulberry result- 

 ing from subdivision of sphere ; 15, 1, 2, 3, 4, diagrammatic representa- 

 tion of transformation of globule into raphis ; 16, a mulberry mass in act 

 of transformation into a fan of raphides. 



Figures 17 to 26. Shows three kinds, 17-21, 22 and 23, 24-26, of metamorphic 

 change accompanied by movements undergone by cholesterin after heating 

 with acetic acid and albumin. 



Figures 27 to 31. Spheres of cholesterin mixed with crystalline matter, from the 

 surface of a biliary calculus. 



Figures 32 to 36. Forms seen after solution of a calculus in ether and slow evapora- 

 tion of the liquid in contact with the pigment. They are transitional 

 from crystal to sphere. 



Figure 37. Diagrammatic section of Biliary Calculus. 1, outer crust dark-coloured 

 without either concentric or radiating structure ; 2, second concentric 

 layer • 3, radiating crystalline layer ; 4, centre, pigmentary, structureless. 



