THE GENESEE FARMER. 



107 



Now it is very evident that the Doctor does not 

 know Avhat he is talking about! Let us take two 

 hundred lbs. of animal charcoal (or charred bones), 

 the very best source of phosphates at present 

 known. If it contains 78 per cent of phosphate, it 

 will be a good article. Leaving out of view the 

 three or four per eeut. of carbonate of lime which 

 has to be converted iuto sulphate of lime before the 

 acid will act on the phosphate, let us see what 

 would be the composition of the ver'y lest super- 

 piiusphate that can possibly be made from this two 

 hundred lbs. of charred bones. 



The 200 lbs. of bones contain 156 lbs. of bone 

 phosphate — composed of 84 lbs. of lime and 72 lbs. 

 of phosphoric acid. To convert this into soluble 

 phosphate, we have to add sulphuric acid enough 

 to take away 56 lbs. of lime. This requires 80 lbs. 

 of sulphuric acid* 



To convert the 156 lbs. of pht)spliate contcained 

 in 200 lbs. of charred bones, then, we add 80 lbs. 

 of sulphuric acid. The mass would then weigh 

 280 lbs. But the sulphate of lime formed by the 

 union of the sulphuric acid and lime, like our 

 common gypsum or plaster, contains two atoms, or 

 about 21 per cent., of water. United wuth the 136 

 lbs. of sulphate of lime found in the mixture, 

 therefore, we have 86 lbs. of water. 



Instead of 280 lbs., therefore, the mass would 

 weigh 316 lbs. Again, as we have before said, the 

 two atoms of lime removed froui the phosphate of 

 lime are replaced by two atoms of water. In 

 converting the 156 lbs. of phosphate of lime into 

 soluble superphosphate, therefore, 18 lbs. of water 

 are required to replace the lime taken away by the 

 sulphuric acid. This is essential. 



In the case assumed, then, we have: 



Charred bones. SOOlbs. 



Sulphuric acid 60 " 



Water (united with the gypsum) 86" 



Water (united with superph jsphate) 18 " 



This contains 172 lbs, of sulphate of lime or 

 gypsum and 118 lbs. of superphosphate of lime, 

 composed, as we have shown, of 72 lbs. of phos- 

 phoric acid, 28 lbs. of lime, and 18 lbs. of water. 

 In other words, the mixture contains 35.3 per cent. 

 of superphosphate of hme,51|- per cent, of sulphate 

 of lime, and 13.2 per cent of other compounds of 

 which we have taken no notice in this calculation. 



It will be borne in mind that our calculation is 

 based upon the supposition that all the phosphate 

 of lime is converted into superphosphate of lime, 

 and that the article is perfectly dry — the water 

 being chemically united with the superphosphate 



* &*iiULl to about 120 Iba. of coouuoa oii of vitriol (Sp. gr., 1,7) 



of lime, etc. And yet we only get 35^ per cent of 

 superphosphate of lime, or 21 per cent, of phos- 

 phoric acid. What, then, does Dr. Lee mean by 

 talking of an article that should contain 56 per 

 cent, of superphosphate? In pra-ctice, such an 

 article as we have described, containing only 35^ 

 per cent., can not be made. There will always be 

 more or less water and free phosphoric acid, aJid 

 undecomposed phosphate, or free sulphuric acid in 

 the mixture. Prof. Wat has made numerous analy- 

 ses of English commercial superphospliates. The 

 average quantity of superphosphate found in the 

 hest four samples was about 21 per cent. — 13.23 per 

 cent of soluble phosphoric acid. For Dr. Lee, then, 

 to talk about a superphosphate of lime containing 

 56 per cent, of soluble phosphates is absurd. 



COAL ASHES AS A MANUBE. 



We are frequently asked, "Are coal ashes of any 

 benefit as a manure." That they are of some 

 benefit, there can be no doubt. Numerous aiuilyses 

 of coal ashes have been made. We have now 

 before us analyses of ashes from seven different 

 kinds of coal. They vary considerably in com])o- 

 sition, but on an average contain about 45 per cent, 

 of silica, 40 of alumina and oxide of iron, 12 of 

 sulphate of lime or plaster, 2 of magnesia, and 1 of 

 phosphoric acid. ' 



Commercially, coal ashes have no value as a 

 manure. But still they are worth something, and 

 ought not to be thrown away. We have seen them 

 produce quite a marked effect on grass land — perhaps 

 as much from their action as a mulch as from any 

 other cause. On stiff clay lands, they are beneficial 

 by rendering the soil more friable and permeable 

 to atmosplieric influences. 



It is said they are good as a top-dressing for 

 lucerne and red clover. They are frequently mixed 

 with night soil for the purpose of absorbing un- 

 pleasant odors. They are often employed in the 

 garden, more for the purpose of forming walks and 

 to prevent the ravages of mice, than as a manure. 

 Covering early sown peas with coal ashes is said to 

 forward their growth, as they have a tendency to 

 absorb and retain heat from the sun. An experi- 

 enced gardener informs us that he uses coal ashes 

 for checking the too rapid fermentation of maimre 

 in hot-beds, and regulating the heat. For radislies, 

 on a rather heavy soil, ccal ashes are very benf ficial. 



In the Gardeners' Magazine^ vol. 11, page 406, 

 an experiment is given where coal ashes were sowu 

 on a row of turnips, which produced a heavier 

 crop than another row manured with well-rotte(} 

 dung. 



