FLAME-HEAT IN THE CHEMICAL LABORATORY, 



ESPECIALLY THAT EEOM GAS, WITHOUT THE AID 

 OF A BLAST. 



There is probably no more important era in the operations 

 of the chemical laboratory than that of the introduction of the 

 lamp as a source of heat for a large number of chemical oper- 

 ations, and that without the aid of a blast. Berzelius was 

 doubtless the first to accomplish much in this direction, which 

 he did by the agency of the lamp that so commonly bears his 

 name, and which, more or less modified, is still in use where the 

 ordinary illuminating gas is not to be had. 



Although illuminating gas has been in use for about seventy 

 years, it is only within a comparatively recent date that it has 

 been pressed into service and used as a heating agent in the 

 laboratory. The reason of this arose from the fact that when 

 burnt in the ordinary manner it deposited soot on the vessels 

 heated by it. This difficulty has been overcome by burning 

 the gas from small orifices made in a tube bent in the form of a 

 circle, the holes being from one to two centimetres apart, and 

 sometimes combining two or more rings in concentric circles. 

 This method, however, has not been generally adopted. 



We must date the successful introduction of gas for heating 

 purposes to the use of a mixture of gas and air passed through 

 wire-gauze and ignited above the gauze, giving a flame without 

 light and with great heat. The invention of this method is 

 claimed by several, and doubtless was discovered by different 

 individuals at about the same time, without a previous knowl- 

 edge of each other's results ; this method is still more or less 

 employed for certain purposes. 



The next step in this direction, and doubtless the most im- 

 portant up to the present time, is to burn the mixture of gas 

 and air without the agency of wire-gauze ; it was first made 

 known to the public in the burner commonly called the Eunsen 



