22 Farmers' Bulletin 1057. 



5 or 10-poiincl can is the best size to buy for home use; larger con- 

 sumers probably can handle the material in larger drums conven- 

 iently and of course more economically. The j^urchaser must make 

 sure that the contents of the drum he contemplates buying are in 

 fragmentary form, for some caustic soda is run into drums in a 

 melted condition and on cooling forms a single solid cake, which is 

 not adapted for the present j)urpose. It always should be purchased 

 under a guaranty of not less than 85 per cent actual caustic soda. 



Caustic soda is an intensely active and powerful substance. "When 

 exposed to the air it strongl}^ attracts moisture, increasing in weight 

 and becoming pasty, while at the same time it becomes contaminated 

 with sodium carbonate through absorption of carbon dioxid. Hence 

 it always must be purchased in original containers, never in bulk; 

 the container must not be opened until just before the material is 

 to be used; the substance must not be allowed to stand exposed to 

 the air, and if any is left over which is to be kept for subsequent 

 use it must be immediately transferred to a tin pail provided with a 

 tight-fitting cover. 



Owing to the intense chemical activity of caustic soda it is ex- 

 tremely corrosive in its effect upon skin or clothes, and upon the 

 lungs if its dust is inhaled. Therefore it is necessary'' to handle it 

 gently to avoid the raising of dust and to wash off at once with water 

 any which may touch the skin or clothing. 



LYE. 



Lye designates a grade of caustic soda put up primarily for domes- 

 tic use, such as making soap from waste grease and for general 

 cleansing. It is sometimes of very inferior quality. If a guaranty 

 regarding its purity can be obtained, it may be used for dip making, 

 in case of necessity, in the same proportions as caustic soda. 



SODIUM CARBONATE. 



Sodium carbonate is sold in a number of forrtis which differ 

 greatly in strength, that is, in the proportion of actual sodium car- 

 bonate they contain. Consequently the cheapest in cost per pound 

 may not be the most economical to use. Soda ash is the strongest, but 

 is not recommended for the home preparation of dips. It is of un- 

 certain strength when purchased and becomes weaker on exposure to 

 air, while in contact with water it lumj)s badly and dissolves slowly, 

 Sal soda is the weakest and probably the least economical form, but 

 because it is so well known and so easily obtained it has been the 

 most generally used form of sodium carbonate for homemade dips. 

 Its relative weakness is due to the fact that almost two-thirds of it 

 is water, combined as " water of crj^stallization." "When fiesh it con- 

 sists of large, nearly transparent crystals, but on exposure to air it 

 tends to fall to a white powder. This change is simply due to the 

 evaporation of the water of cryslalli/ation. and consequently the 



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