MISCET.LANEOUS PAPERS. 273 



upon the fact that it is an essential element of nutrition ; the substance which 

 we apply to the land with a view of increasing our crops may have no value 

 whatever as a direct fertilizer, and may, as in the case of chloride of sodium, 

 not even make its appearance in onr grain cro[)s, and yet it may be instrumen- 

 tal in materially raising the produce of wheat. 



"Again, such non-essential salts in general may nevertheless play an impor- 

 tant part in the nutrition of plants by assisting the solution and uniform 

 distribution of fertilizing constituents which occur in the soil in a s[)aringly 

 soluble or insoluble condition. It is well known to chemists that chloride of 

 sodium exercises a dissolving action upon sound bodies, and thus it is not too 

 great a stretch of fancy to assume that it will act beneficially in llie field by 

 dissolving and rendering available e:irthy fertilizing constituents whicli without 

 its aid will remain in an inert condition for a long time." [Journal Royal Ag. 

 Soc, 2d series, Vol. I., p. 299, 30-;!. 



The fact so clearly pointed out by Prof. Voelcker, that salt has a marked 

 tendency to prolong the period of vegetative growth and thus to prevent the 

 premature ripening of leaf ;nid consequent arrest of development of the bulbs 

 of root crops, likewise preventing the too rapid ripening of grains, will serve 

 to explain some of the benefits derived from the use of salt as manure; it will 

 also explain why salt is so often beneficial on dry and quick soils, and in dry 

 seasons, and why, on the other hand, so little benefit has been secured in using 

 it on wet, tenacious and cold lands, like most of our boulder clays, or in very 

 wet seasons. 



This prolonging of the period of vegetative growth, and the stiffening influ- 

 ence on ripening straw by which lodging and consequent shrinking of the berry 

 of the grain are prevented, are well recognized effects of salt as manure, and 

 will serve in part to point out the conditions under which we may expect benefit 

 from its use as manure. 



Its solvent action on the insoluble mineral substances in the soil is also of 

 importance in estimating the value of salt as manure. 



AGRICULTURAL USES OF REFUSE SALT. 



In discussing the influence of salt as a manure, we have mainly confined our 

 attention to chloride of sodium, or pure sea salt. The salt that we find in the 

 market, however, is never absolutely pure chloride of sodium, but always con- 

 tains a small amount of foreign materials, such as suljjhate of lime, chloride 

 of calcium and of magnesium. If it contains even one part in a hundred of 

 chloride of calcium or magnesium, sulphate of magnesia or soda, it would be 

 considered unfit for table use because of its bitterness ; or if it contains carbon- 

 ate of lime or magnesia, it would be unfit for preserving meat. It is the aim 

 of the salt boiler as far as possible to separate these foreign materials from his 

 salt in the process of manufacturing, and he is put to considerable expense and 

 trouble to do this, and the State requires that salt shall be inspected to see 

 that this purification is carried to a reasonable extent. Tiie result is that our 

 commercial salt is a very pure article indeed, seldom containing more than one 

 or two per cent of solids other than chloride of sodium. 



We have seen that the agricultural chemist objects to salt as a manure because 

 it is so pure — l^ecause it contains almost nothing but chloride of sodium — and 

 he can hardly forgive it for being common salt at all. If it was anything ekie 

 — sulphate of .soda, of linie, or of magnesia, chloride of potassium or magne- 

 sium — anything but common salt, he could find something to say in its favor. 

 35 



