THE COMPLETE GKAZIER. BOOK xi. 



as a more highly basic and much more readily available kind of 

 phosphate. Good samples of basic slag which is also known as basic 

 cinder, and as Thomas's phosphate powder contain from 14 to 18 per 

 cent, of phosphoric acid. 



ACID AND NON-ACID PHOSPHATIC MANURES. Is it better to use raw 

 or undissolved phosphatic manures, such as bones, phosphatic Peruvian 

 guano, and basic slag, or to employ acid manures, like dissolved bones 

 and superphosphate ? This is a question which for some years has 

 occupied much attention, and has been the subject of many experiments. 

 At one time it was generally supposed, both by farmers and agricultural 

 chemists, that dissolved manures, like superphosphate, were invariably 

 to be preferred. Of late years, however, both here and abroad especially 

 abroad it has been recognised that on some soils and for some purposes 

 raw or undissolved phosphatic manures answer quite as well. Indeed, 

 careful comparative experiments have shown that sometimes undissolved 

 or non-acid manures give better results. How, then, are we to decide 

 in any given case ? Speaking broadly, and with some reservations, the 

 rule may be laid down that for all crops where the soil possesses a fairly 

 abundant quantity of lime, superphosphate is usually found the most 

 economical and efficacious phosphatic manure ; while on soils decidedly 

 deficient in lime we should recommend bone meal, raw phosphatic 

 guano, or basic slag. On such land, and particularly for grass, slag has 

 repeatedly proved highly remunerative. 



How are we to tell when a soil is wanting in lime ? Chalky or marly 

 soils, of course, are essentially calcareous or limy, and there we have no 

 doubt. Moorland soils, heaths, and sandy granitic soils are generally, 

 on the other hand, very poor in lime. But the average clay or loam, 

 for aught we can tell from its appearance, unless we are versed in the 

 vegetative indications of scarcity of lime, may or may not contain a fail- 

 quantity' of lime. Of course a chemical analysis of the soil will 

 indicate precisely how much lime is present, but there is a rough and 

 ready way of forming a very fair idea on this point which any careful 

 man can employ for himself, without calling in the aid of the professional 

 chemist. Let a few clods or spits of the soil, taken from various parts of 

 the field, be dried, crumbled, and well mixed together, and a few ounces 

 of the dried soil then taken and powdered to a moderate degree of fine- 

 ness. Let this be burnt to ashes at a low red heat in an iron shovel over 

 the fire, cooled, and put into a tumbler. Next mix it thorough^ with 

 water to a thin paste, using sufficient water to well cover the burnt 

 earth, and let it be well stirred with a glass rod or wooden penholder 

 (not with a spoon or anything metallic) until air-bubbles no longer- 

 escape. Then let the operator pour in an ounce or so of hydrochloric 

 acid (commonly sold as muriatic acid, or spirit of salt), and at the 

 same time keep the mixture stirred. If the mixture effervesces fairly 

 briskly, it may be taken that the soil contains a fair proportion of lime. 

 If, on the other hand, there is little or no effervescence, it may be taken 

 that the land is deficient in lime. In the former case, speaking as a 

 genera] rule, we should recommend the use of superphosphate, dissolved 



