720 



dressing, it should be thoroughly mixed with six or seven times its- 

 bulk of soil to ensure an equal distribution. It has the effect of 

 increasing the grain yield without any detriment to the straw. 



It is stated by some authorities that by steeping seeds in a 

 solution of sulphate of ammonia the crop is greatly increased, more 

 especially with potatoes, which are said to have given phenomenal 

 crops. This action is said to hasten germination, to supply readily- 

 available nourishment to the embryo plant and hasten a healthy 

 growth to the young plant when it is most liable to disease, thus 

 enabling it to resist and overcome the attack of pests. The best 

 solution to use is i Ib. of ammonium sulphate, i Ib. potassium 

 nitrate, and 5 galls, of water. There are other authorities who 

 either deny or doubt any such benefit from the steeping of seed in 

 a solution of ammonia. At the present time the matter is so much 

 in dispute that, until further investigations are made, the value of 

 the solution must remain a matter of opinion. 



Until we have dealt with nitrate of soda and potash we will 

 postpone any comparison between ammonium sulphate and 

 nitrates. 



SODIUM AND POTASSIUM XITRATE. 



Nitrate of soda is principally obtained from the west coast of 

 Southern America, Peru, Chili, and Bolivia. It is sometimes called 

 Chili nitre and Chili saltpetre. It is found in the desert or barren 

 sand that stretches from north to south for over 600 miles along 

 the foot of the Cordilleras. The sand is lixiviated with water to 

 extract the nitre, the solution is then evaporated. The crude salt 

 obtained is called caliche. It has the following composition,, 

 according to Roscoe and Schorlemmer : 



Sodium nitrate ... 

 ,, sulphate 

 ,, chloride 



iodide ... 

 Calcium sulphate 

 Magnesium sulphate 

 Insoluble matter 

 Moisture 



64-98 



3-00 



28-69 



2-70 



lOO'OO 



II. 

 27-85 



18-30 



68 



4-20 



(roo 



IOO'^ 



The caliche sand does not rise to the suriacc, and is generally 

 covered with two layers. The top layer or chuca consists of sand 

 and gypsum, while the intervening layer called costra is a con- 

 glomerate of clay and breccia or small fragments of rocks. The 

 caliche when pnrilicd generally contains from 1)5 to u<S per cent. 

 of nitrate of soda. The purified salt is greatly used for the manu- 

 facturing of sulphuric and nitric acids, also for making nitrate ol 



