578 Mr. H. D. Murray on the 



E. Tetranitro aniline. 



XIII. 





XIV. 





XV 





At 140°. 



At IS 









Time in 



Per cent. 



Time in 



Per cent. 



Derived 



curve 



from XIV. 



hours. 



t. 



decomposed. 

 sc. 



hours. 



t. 



decomposed. 



X. 



x. 





dx 



3 



10 



21 



0-93 







dt' 



5 



1-5 



45 



2-29 



•5 





•044 



21 



10-5 



70 



4-56 



1-6 





•057 



24 



,16-0 



94 



7'89 



3-4 





•091 



28-5 



29-5 



118 



12-12 



62 





T39 



43 



87-0 



142 



1727 



io-o 





•176 



49 



95-5 



167 



2440 



13-9 





•214 



67 



990 



189 



32-08 



20-8 





•286 



72-5 



100 



214 



43-47 



28-2 





•349 



75 



100 



239 



5776 



37-8 





•456 







262 



73-29 



50-6 





•572 







287-5 



94-3 



655 





•672 







310-5 



98-4 



83-6 





•824 







330-5 



991 



96-4 





•179 







337 



100 



99-6 





■04 







354-5 



100 



100 









Fig. 5, Curve 



Fig. 5 



Curve II. 



Fig. 



5, Curve III. 



LXVIII. llie Precipitation of Colloids. By Humphrey D. 

 Murray, Exhibitioner of Christ Church, Oxford *. 



THE author has recently attempted to obtain a general 

 expression for the precipitating effect of ions on 

 colloids. Whilst the attempt has not at present been 

 successful in discovering a general relationship, a special 

 case has been found for which the expression reduces to a 

 simple equation. This, as derived, is applicable only to the 

 effect of univalent cations with the same anion upon the same 

 colloid under equal conditions of temperature and concen- 

 tration, the colloid carrying a negative charge. It relates 

 the concentration ot the cation in gm. atoms required to 

 precipitate the whole of the colloid in a given time, with the 

 atomic number of the cation, and is of the form 



where C represents the concentration of the cation, 

 N represents the atomic number of the cation, 

 n is constant for the colloid at that particular con- 

 centration, 

 K is a constant depending upon the nature of the 

 colloid and the anion. 



* Communicated by the Author. 



