4 farmers' bulletin 603. 



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

 exposed to the air it strongly 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 must always be purcliased in original containers, never in bulk; 

 the ciDntainer 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 

 tightly fitting cover, such as a lard pail, or, l^est of all, a paint pail 

 with a friction top. 



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 dust from it is inhaled. Therefore it is necessai*y to handle it 

 gently to avoid the raising of dust and to wash off at once with wat^r 

 any which may touch the skin or clothing. 



Gmiatic potash. — Also known as potassium hydroxid or hydrate, is 

 ver}'^ similar in its properties to caustic soda. It is not, however, so 

 widely used industrially, and is decidedly more expensive without 

 being any better for the present purpose. Therefore it should be 

 purchased only when caustic soda happens not to be available. In 

 its use one must remember that, weight for weight, it is less efficient 

 than caustic soda, so that for every pound of the latter there must be 

 employed 1.4 pounds of caustic potash. Like ciiustic soda, it must be 

 guaranteed at least 85 per cent pure. 



Lye. — This is a term employed to designate a grade of caustic soda 

 put up primarily for domestic use, such as making soap from waste 

 grease and for general cleansing. Since ordinary' buyers of this 

 grade of goods are not apt to be able to judge closely of its quality, 

 it is sometimes of very inferior grade, though not necessarily so. 

 If any guarantj^ regarding its purity can be obtained, it may be used 

 for dip making, in case of necessity, in the same proportions as 

 caustic soda. 



THE GENERAL COMPOSITION OF DIPS. 



All arsenical cattle dips contain arsenious oxid as the active tick- 

 killing agent. But since straight areenious oxid, that is, white ar- 

 senic, is so slightly and slowly soluble in water, it is necessary to use 

 some othei' chemicnl agent, such as sodium carbonate or hydro.xid, to 

 bring the arsenious oxid into solution. In this way the white arsenic 

 is changed to sodium arsenite if either sodium hydroxid or sodium 

 carbonate is employed, or to potassium arsenite if (he corresponding 

 potassium compounds are used. Starting with a given weigiit of 

 white ai'senic, whethei- il is converted to sodium arsenite or to potas- 

 s-ium ai-senile appears to maki' lu) difference in the action of the 

 finislie() dip. 



