54 



angle of repose of the material. This increase of pressure 

 diminishes in inverse proportion to the height, and ceases when 

 the height of the imaginary cone is reached, all the weight of 

 additional height above that point, being borne by the retaining 

 frames. In the model, the " wall " and framework are in a cast- 

 iron vessel, which is heated in a brick furnace. The porous 

 material is distributed to, and gathered from, the wall, by 

 covering and inverted cones from, and to, central pipes. The 

 gaseous current passes from the outside of, and through, the 

 "' walls " to the space they and the covering cone enclose, and is 

 withdrawn from this space, or the direction of the current is 

 reversed at pleasure. 



172. Carbolic acid, chemically pure, free from taste and 

 smell of tar, and fusing at 108 Fahrenheit. Specially 

 prepared for internal medicinal use. 



1876. Exhibited by F. C. Calvert $ Go. 



173. Carbolic acid, commercial, fusing at 95 Fahren- 

 heit. Specially prepared for external medical application. 



1876. Exhibited by F. 0. Calvert $ Co, 



174. Cressylic acid, used for disinfecting purposes. 

 1876. Exhibited by F. C. Calvert $ Co. 



175. Sulpho-carbolates. A series of pharmaceutical 

 products, comprising sulpho-carbolates of potash, soda, 

 ammonia, lime, iron, copper, zinc, and alumina. 



1876. ' Exhibited by F. C. Calvert $ Co. 



176. Carbolic acid preparations, comprising carbolic 

 acid soap, carbolic acid disinfecting powder, and carbolised 

 tow. 



1876. Exhibited by F. C. Calvert Sf Co. 



177. Picric acid crystals and paste used in the arts. 

 1870. Exhibited by F. C. Calvert $ Co. 



178. Crystalline aurine. 



1876. Exhibited by F. C. Calvert $ Co. 



179. Oxalic acid. Two specimens. One crystallised 

 from a solution containing sulphuric acid, the other 

 from an aqueous solution. 



1876. Exhibited by Roberts, Dale, $ Co. 



This product is made by the action of caustic potash, or a 

 mixture of caustic potash and caustic soda on woody fibre 

 (sawdust). The result of this action is oxalate of potash. The 



