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EXPERIMENTAL PHARMACOLOGY 



special aluminum solder must be bought. Xo acid is used 

 in aluminum soldering but the scraped metal surfaces are 

 heated and the aluminum solder is rubbed on the proper 

 places with the (very) hot soldering copper. The author 

 has not found a blast lamp very satisfactory for aluminum 

 soldering. 



For ordinary soldering on brass, etc., a small flame from 

 the blast lamp is best. Fig. 377 shows the method of ap- 

 plying the flames in making a brass T-tube or tracheal 



Pig. 37;. Method of preparing two pieces of brass tubing for making a tracheal cannula. 



and the process used for holding and soldering the pieces together. 



cannula. But soft solder will not stick to the brass, etc., 

 unless a soldering acid is used. This soldering acid or 

 fluid is made by placing granulated zinc in hydrochloric 

 acid and allowing the acid to dissolve all of the metal pos- 

 sible. An excess of zinc should be left in the bottom of the 

 bottle. The acid is applied to the article by means of a 

 glass tube used as a pipette. Fig. 377 also shows the two 

 pieces of brass tubing which have been filed (or sawed) off 

 of a long brass tube. These two short pieces are filed with 

 a round file as shown in the illustration, an opening being 



