LABORATORY SUPPLIES AND CHEMICALS 



297 



The Thermit reaction is based on the chemical formula Fe2O 3 +2Al=2Fe-j-Al 2 O. 

 In other words, iron oxide mixed with aluminum in approximately volumetric pro- 

 portions and in the proper state of division will react in such a way that the oxygen 

 leaves the iron oxide and combines with the metallic aluminum with which it forms 

 an aluminum oxide or slag, setting free the iron. 



The essential characteristic of the process is that when the Themit mixture is 

 ignited in one spot, the combustion so started continues throughout the entire mass 

 without supply of heat or power from outside, and produces superheated liquid steel 

 and superheated liquid slas?. The temperature produced by the reaction attains about 

 4881 F in less than thirty seconds. The liquid steel produced by the Thermit 

 reaction represents one-half of the original Thermit by weight and one-third by 

 volume. 



. In order to ignite Thermit, place on top of it a small heap 



of special ignition powder. Place on top of the powder a 

 parlor match, so that the head of it will come about over the 

 center of the powder, ignite the head of this match by applying 

 another parlor match. Care must be taken as the reaction 

 takes place instantaneously. 

 Welding a Small Boss to a Steel Plate by Igniting the Thermit Directly on the Plate 



The materials necessary are 

 a steel plate, a refractory 

 pouring cup, the necessary 

 quantity of Themit (welding 

 portion No. 1 in can) and 

 one-half teaspoonful of igni- 

 tion powder. Place the plate 

 on some dry sand and put one 

 of the pouring cups anywhere 

 on the plate after taking care that the place selected is free from dirt or rust. Then 

 fill the pouring cup about half full of Thermit and ignite as described above. The 

 Thermit will burn down rapidly, giving off a bright light. It is advisable to protect 

 the eyes with dark glasses. When the reaction has been well started, feed in the 

 balance of the Thermit from the can in a steady stream so as to keep the reaction 

 going until the entire welding portion has been consumed. About two minutes 

 after the experiment has been made, tap the pouring cup gently with a hammer so as 

 to break it up. It will be found that a lump of steel has been welded to the plate. 

 Materials required: A 3/16" steel plate. D 2 pouring cups. J 2 cans Thermit 

 and can of powder. 



Burning a Hole Through a 

 Plate 



This experiment demon- 

 strates the intense heat con- 

 tained in the Thermit steel 

 and incidentally teaches the 

 proper manner of closing the 

 outflow of the crucible (plug- 

 ging the tap hole) and tap- 

 ping the same when the re- 

 action is completed. 



The materials necessary for 

 two operations are: 

 B A steel plate % in. thick, 



., nnn 



2 welding portions (W. P. 



N-.l't'apping spade 



T 1 crucible (size 2-A). 



G 4 packages plugging ma- 



terial. 



J 1 bottle ignition powder. 

 I 1 pair dark glasses. 



Price List of Materials for Experiments 



A 3/10-in. steel plate 8x3 in., each. .$O.3O 

 B %-in. steel plate 9x9 in., each... l.OO 

 C ^4-in. steel plate 9x9 in., each... 1.55 



D^Pouring cups, each 25 



E Crucible, No. 2-A, each 8.OO 



F Tripod, No. 1, each 2.75 



G Plugging material, per pkg., each .20 



H Tapping spade, each 30 



I Dark glasses in case, each 35 



J Ignition powder, small bottle, ea. .25 

 K Ignition powder, large bottle, 2 oz. .50 

 Jj Fire-brick molds, each .50 



M Bag of luting sand, each 



NT Welding Portion No. 1, each 



O "Welding Portion No. 2, each 



P Welding Portion No. 3, each 



Q, Welding Portion No. 4, each 



R 1-in. Standard Pipes 6 in. long, 



per pair, each 



S 1 in. Standard Mold, each 



T 1 crucible (2-S), each 



U 1 pair tongs, each 



V 1 pair clamps, each 



$0.10 



.30 



3.00 



3.20 



.60 



.30 

 2.00 

 3.00 



2.00 

 25.00 



Write for Booklet of Experiments 



