in. TEACHING (TECHNICAL). 515 



in inverse proportion to the height, and ceases when the height of the imagi- 

 nary cone is reached, all the weight of additional height above that point 

 being borne by the retaining frames. In the model, the " wall " and frame- 

 work 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 in- 

 verted 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 cone enclose, and is withdrawn from this space, or the direction of the current 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. 



2463. Carbolic Acid, chemically pure, free from taste and 

 smell of tar, and fusing at 108 Fahrenheit. Specially prepared for 

 internal medicinal use. F. C. Calvert fy Co. 



2464. Carbolic Acid, commercial, fusing at 95 Fahrenheit. 

 Specially prepared for external medical application. 



F. C. Calvert $ Co. 



2465. Cressylic Acid, used for disinfecting purposes. 



F. C. Calvert $ Co. 



2466. Sulpho-Carbolates. A series of pharmaceutical pro- 

 ducts, comprising sulpho-carbolates of potash, soda, ammonia, 

 lime, iron, copper, and zinc. F. C. Calvert fy Co. 



2467. Carbolic Acid Preparations, comprising carbolic 

 acid soap, carbolic acid disinfecting powder, and carbolised tow. 



F. C. Calvert fy Co. 



2468. Picric Acid Crystals and paste, aurine, rosolic acid. 

 Used in the arts. F. C. Calvert $ Co. 



2469. Drawings (4) of Hargreaves and Robinson's 

 Sulphate of Soda Apparatus. 1. General plan. 2. Enlarged 

 sectional plan. 3. Transverse sectional plan. 4. Condensing 

 apparatus. Accompanied by 



2470. Samples of: A. Salt prepared for the converting 

 cylinders above. B. Sulphate of soda. C. Hydrochloric acid. 



J. Hargreaves fy T. Robinson. 



Sulphurous acid, steam and air, are made to react upon salt directly, pro- 

 ducing sulphate of soda and hydrochloric acid, without the preliminary 

 manufacture of sulphuric acid. The salt is placed in the iron cylinders, and 

 the mixture of sulphurous acid, air, and steam passed through it. The 

 evolved hydrochloric acid is taken out at the bottom of the cylinders, and 

 conveyed to the condensers. 



2471. Samples illustrative of Mond's process for the recovery 

 of sulphur from alkali (vat or tank) waste : 



1. Alkali (vat or tank) waste before oxidation. 



2. Alkali (vat or tank) waste after oxidation. 



Kk 2 



