i6o Cincinnati Society of Natural History. 



Another factor which has contributed largely to the 

 onward progress of this new work is the perfecting of ap- 

 paratus for laboratory work. This enables the workers to 

 obtain very high temperatures and strong pressures under 

 conditions of almost perfect securit3\ 



For high temperatures, prolonged for a considerable time, 

 it was necessary to have recourse to the furnaces of industry, 

 which are manifestly inconvenient. The employment of the 

 vSchloesing furnace permitted to obtain in the laboratory very 

 high temperatures, using illuminating gas as the combustible. 

 The combination furnaces of Leclerc and Forquignon (1875), 

 and three years later the tube of Damorseau, furnishing a 

 draft by a current of gas, secured very high temperatures in 

 a small space, and maintained these without variation. 



The strong pressures are obtained in tubes of glass, sealed 

 by a lamp, and heated to 200 degrees. A first improvement 

 consisted in inclosing them in metallic coverings hermetically 

 sealed and containing a small quantit}' of water. Daubree 

 attained thus a temperature of 350 to 500 degrees. The iron 

 and brass first used were altered by the water, so Friedel and 

 Sarasin doubled the tube and lined the interior with platinum. 

 The hermetical closure of the tube caused great difficulty for. 

 a long time. Friedel and »Sarasin overcame this by using a 

 platinum band fastened around the circumference of the 

 mouth of the tube as a loop, and fastened by bolts on the 

 sides. Foque and Levy have modified this by changing the 

 disc and obtaining the pressure by a stirrup which rests upon 

 the loop and presses firmly to its place the steel plate at the 

 top of the tube. This method of closing they find perfectly 

 safe, and it resists pressures which rend the tube, whose 

 walls are one centimeter thick, with interior diameter of the 

 same size. Friedel and Sarasin improved this by applying 

 the closure to both ends, so facilitating the cleaning of the 

 interior. The next improvement was made by Wiesnegg, 

 who, in i<S79, designed a stove, in which, with coal gas as fuel, 

 many such tubes could be heated at the same time to a tem- 

 perature near 500 degrees. Automatic valves were con- 

 structed, regulating supply of gas so as preserve a uniform 

 temperature. 



It is seen by this review of growth that the first workers 

 in the field were chemists, and tlie difference between a chem- 



