130 W. KAMSAY ON THE PRECIPITATION 



ties determined. A measured quantity of the muddy water was 

 added to each solution, and the rates of settling compared with one 

 another. It was found impossible to obtain any definite measure 

 of the rates of settling ; for neither by weighing the clay which had 

 settled in a given time,, nor by comparing one stratum of mud 

 settling in one solution of salt with another stratum in another salt 

 solution, could a reliable measure be obtained. It was always easy, 

 however, to pronounce which was settling most quickly. 



The results will be seen in the following Table. In each case 

 one part of salt by weight was dissolved in four parts of water. 

 The salts are arranged in the order of settling, those in which the 

 clay subsided most quickly being placed first, with regular progres- 

 sion to the one which kept the mud longest in suspension. 



Seduction of temper- Specific gravity of 

 Salt. ature on dissolving, solution at 10° C. 



Ammonium chloride 15-19 C. 1*0604 



Ammonium nitrate 14-10 1*0863 



Potassium chloride 11*81 1*1361 



Sodium nitrate 9*46 1*1355 



Barium chloride 4*50 1*1733 



Magnesium sulphate 4*50 1*1035 



Zinc sulphate 3*10 1*1258 



Sodium chloride 2*10 1*1513 



Lead nitrate 1*90 1*2099 



It will be at once seen that those salts which absorb most heat on 

 going into solution allow clay to deposit most easily. 



In order to ascertain if the fluidity of the solution had any 

 influence on the rate of settling, the rate of flow through a capil- 

 lary tube, of the following six salts, was determined. The numbers 

 arc seconds, and arc simply comparative. The temperature for all 

 was 15° C. ; and there was a constant pressure of one metre of 

 water. 



Time of flow through 

 Salt. a capillary tube. 



seconds. 



Ammonium chloride : . . 370*0 



Ammonium nitrate 366*0 



Potassium chloride 381*0 



Sodium nitrate 456*0 



Barium chloride 455*0 



Sodium chloride 554*0 



Water 380-0 



The order holds good for several of the salts, but it is not constant 

 enough to allow of the deduction of a general rule. A connexion 

 appears, however, to subsist between the fluidity of the solutions 

 and. their absorption of heat on being dissolved. Water flows more 

 rapidly through a capillary tube than any of the solutions, except 



