104 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



heap with this solution, stirring with the shovel until all the grains are 

 well moistened. Then spread 2 kilogrammes (4"4 lb.) of lime recently 

 slaked over the moistened grain, and stir the heap until all the grains 

 are covered with a layer of lime. Hequet d'Herval declares that the 

 success of this treatment is complete, and Loverdo regards this process 

 as that which gives the best result, after Kuhn's blue vitriol disinfection 

 process. Sulphate of soda is, moreover, less injurious to the grain than 

 blue vitriol. Comes has slightly modified this treatment and advises 

 that the spraying of the heap of grain be replaced by immersion in a 

 solution of sulphate of soda. It suffices to immerse the seeds in a 

 concentrated solution of sulphate of soda so that they are completely 

 covered, then add milk of lime and stir for two hours, then spread the 

 grain out to dry. G. Arieti estimates that sulphate of soda has a 

 more injurious action on the spores of Tilletia (bunt) than sulphate of 

 potash. He advises not to exceed a 2 per cent solution for the sake 

 of the vitality of the grain, this quantity being quite sufficient to fulfil 

 the object of sulphating (pickling). 



25. Sodium Chloride (Common Salt), NaCl.^ — Occurrence. — 

 Common salt is found crystallized in thick beds in certain countries. 

 It also occurs in solution in sea-water and certain springs. The mines 

 of rock salt of Cordofia (Spain), those of Wieliczka and of Bochnia in 

 Poland, contain large quantities, and the purity of the product is so 

 great that it suffices to pulverize the salt of these mines to impart to it 

 a commercial form. A large amount of the salt used in commerce is 

 obtained by the evaporation of sea-water. This operation is conducted 

 on the horizontal surface of a clay soil. To facilitate the feeding of 

 these basins they are placed below sea-level and form " Salines ". 

 Those of the Mediterranean extend from Hyeres as far as Port Vendres. 

 The evaporation of the sea-water is generally conducted in basins in 

 which are deposited, until sufficiently concentrated, the different salts 

 less soluble than common salt likewise found in solution in that water. 

 Finally, it is run in layers of 5 centimetres into the smallest basins 

 called " tables salants " (salt table), in which the salt crystallizes. The 

 mother liquors are run off and the salt is lifted out by special flat 

 shovels. 



Properties. — Salt is met with as anhydrous crystals. The degree 

 of solubility of the salt in water varies little, whatever be the tempera- 

 ture ; 100 grammes of water at 18° C. dissolve 36 grammes of salt, and 

 at 100° C. 40 grammes. Its use is necessary in the nutrition of the 

 animal ; administered in too high a dose, it cannot be eliminated by the 

 skin, the kidneys, and the intestines, and remaining accumulated in 

 the blood it may coagulate the albumen. 



Role of Common Salt. — According to Sachs, Peligot, and Fraisse, 

 sodium chloride or its elements, with few exceptions, are present in 

 almost all plants. A feeble dose of common salt may thus act as 

 a manure for plants, but a strong dose may be so injurious as to kill 

 them. Braconnot, Schubler, and Meyer have shown that if the quantity 

 of salt used exceeds a certain dose, it stops germination of the seed 

 and the growth of plants. Dieterich proved that big doses of salt 

 completely paralyse the first phases of plant life, and prevent the 



