27 



were chosen because the Amorphous Calcium Oxalate first 

 produced on mixing these solutions rapidly becomes 

 crystalline, and the effect could not be surmised on mixing 

 with a capillary tube. The usual phenomena took place 

 until the tube reached tlie height of about one inch, when 

 the Amorphous Calcium Oxalate suddenly changed to the 

 crystalline variety, and apparently stopped the action, as no 

 further upward growth took place. On careful examination, 

 however, of the point of the growth, a fluid was noticed to 

 emerge which had no action on the surrounding Calcium 

 Chloride, showing that chemical action was still going on. 

 Now, the upward growth having ceased, it was inevitable 

 that the tube should become wider, and this is what really 

 took place. On another experiment I obtained a nearly 

 spherical body, about half an inch in diameter. 



5. Action of Ammonia on Ferrous Sulphate. A very 

 thick tube of Ferious Oxide was formed, which I am able 

 to show you, as it is by no means fragile. It has of course 

 been since, out of the fluid, partially converted into Ferrous 

 Oxide. 



6. Sodium Carbonate on Copper Sulphate. In this case 

 a crystalline Copper Carbonate was obtained of two shades, 

 one a bright blue, resembling Azurite (if it be not actually 

 that substance), and another a bright green, resembling 

 Malachite. I am able to show this tube. 



7. Ammonium Sulphide on Copper Sulphate. An action 

 closely resembling in many particulars the action of 

 Ammonia on Ferrous Sulphate. 



8. Sodium Carbonate on Calcium Chloride. The com- 

 mencement of the action was marked by the formation of a 

 perfectly transparent and highly refractive sheath of Calcium 

 Carbonate, which did not show any signs of crystallization 

 until about half an inch in length. On examination after 

 the lapse of about twelve hours, a crystalline tube of 

 Calcium Carbonate had made its way to the top of the 



