656 



FARMERS' REGISTER, 



[No. 11 



exist in the poil derived from these rocks. It is a 

 constituent, likewise, of" almost every kind of ani- 

 mal and vefTCfable manure. 



Besides these compounds of the alkaline earths 

 and alkalies, many others have been recommend- 

 ed for the purpose of increasintj vegetation ; such 

 as nitre, or the nitrous acid combined with polassa. 

 Sir Kenelm Dicby states, that he made barley 

 ^row very luxuriantly by watering it with a very 

 weak solution of nitre ; but he is too speculative a 

 writer to awaken confidence in his results. This 

 substance consists of one proportion of azote, six 

 of oxygen, and one of potassium ; and it is not 

 unlikelj' that it may furnish azote to form albumen 

 or gluten in those plants that contain them ; but 

 the nitrous salts are too valuable /or other purposes 

 to be used as manures. 



Dr. Home states ihnt sulphate of potassa, which 

 as I just now mentioned is found in the ashes of 

 Bome peats, is a useful manure. But JMr. Nais- 

 mith* questions his results ; and quotes experi- 

 ments hostile to his opinion, and, as he conceives, 

 unfavorable to the efficacy of any species of sa- 

 line manure. 



Much of the discordance of the evidence rela- 

 ting to the efficacy of saline substances depends 

 upon the circumstance of their having been used 

 in different proportions, and in general in quanti- 

 ties much too large. 



I made a number of experiments in May and 

 June, 1807, on the eflects of different saline sub- 

 stances on barley and on grass growing in the 

 same garden, the soil of which was a lisht sand, 

 of which 100 parts were composed of 60 parts of 

 siliceous sand, and 24 parts finely divided matter, 

 consisting of 7 parts carbonate of lime, 12 parts 

 alumina and silica, less than one part saline mat- 

 ter, principally common salt, with a trace of gyp- 

 sum and sulphate of magnesia: the remaining 

 16 parts were vegetable matter. 



The solutions of the saline substances were used 

 twice a week in the quantity of two ounces, on 

 spots of grass and corn, sufficiently remote from 

 each other to prevent any interference of results. 

 The substances tried were super-carbonate, sul- 

 phate, acetate, nitrate and muriate of potassa; sul- 

 phate of soda, sulphate, nitrate, viuriate, and car- 

 bonate of ammonia. I found that in all cases 

 when the quantity of the salt equalled tj'j, part of 

 the weight of the water, the effects were injuri- 

 ous; but least so in the instances of the carbonate, 

 sulphate, and muriate of ammonia. When the 

 quantities of the f^alts where gi^ part of the solu- 

 tion, the effects were different. The plants wa- 

 tered with the solutions of the sulphates grew just 

 in the same manner as similar plants watered 

 with rain water. Those acted on by the solution 

 of nitre, acetate, and supercarbonate of potassa, 

 and muriate of ammonia, grew rather better. — 

 Tliose treated with the solution of carbonate o( 

 ammonia grew most luxuriantly of all. This last 

 result is what might be expected, for carbonate of 

 ammonia consists of carbon, hydrogen, azote, 

 and oxygen. There was, however, another result 

 which I had not anticipated ; the plants watered 

 with solution of nitrate of ammonia did not grow 

 better than those watered with rain water. The 

 solution reddened Utmus paper ; and probably the 



* Elements of Agriculture, p. 78. 



free acid exerted a prejudicial effect, and interfer- 

 ed with the result. 



Soot doubtless owes a part of its efficacy to the 

 ammoniacal salt it contains. The liquor produced 

 by the distillation of coal contains carbonate and 

 acetate of ammonia, and is said to be a very good 

 manure. 



In 1808, 1 found the growth of wheat in a field 

 at Roehampton assisted by a very weak solution 

 of acetate of ammonia. 



Soapers' waste has been recommended as a ma- 

 nure, and it has been supposed that its efficacy de- 

 pended upon thedifferent saline matters it contains ; 

 but their quantity is very minute, indeed, and its 

 principal ingredients are mild lime and quicklime. 

 fn the soapers' waste from the best manulactories, 

 there is scarcely a trace of alkali. Lime moistened 

 with sea-water affords more of this substance, and 

 is said to have been used in some cases with more 

 benefit than common lime. 



Mr. Knight informs me, that he has foand, in 

 the two last seasons, that pond mud, of very poor 

 quality, chiefly clay, having been mixed with coal 

 dust, to afford fuel for his hot-houses, afforded a 

 manure of considerable power. It acts, however, 

 much more beneficially upon soils which are in 

 tolerably good condition, and perhaps rather sti- 

 mulates than feeds; for on very poor soil, where 

 some was laid in the last winter, its eJiiects can 

 scarcely be perceived. 



It is unnecessary to discuss to any greater ex- 

 tent the effects of saline substances on vegetation; 

 except the ammoniacal compounds, or the com- 

 pounds containing nitric, acetic, and carbonic acid, 

 none of them can afford by tlieir decomposition 

 any of the common principles of vegetation, car- 

 bon, hydrogen, and oxygen. 



The alkaline sulphates and the earthy muriates 

 are so seldom found in plants, or are found in such 

 minute quantities, that it can never be an object 

 to apply them to the soil. It was stated in the be- 

 ginning of this lecture, that the earthy and alka- 

 line substances seem never to be formed in vege- 

 tation; and there is every reason likewise to be- 

 lieve that they are never decomposed; for after be- 

 ing absorbed they are found in their ashes. 



The metallic bases of them cannot exist in con- 

 tact with aqueous fluids; and these metallic bases, 

 like other metals, have not as yet been resolved 

 into any other forms of matter by artific^ial pro- 

 cesses; they combine readily «vith other elements; 

 but they remain undestructible, and can be traced 

 undiminished in quantity, through their diversified 

 combinations. 



LECTURE VIII. 



ox THE IBIPROVEMENT OF LANDS BY BURN- 

 ING; CHEMICAL PRINCIPLES OF THIS OPE- 

 RATION. ON IRRIGATION AND ITS EFFECTS. 

 ON FALLOWING; ITS DISADVANTAGES AND 

 USES. ON THE CONVERTIBLE HUSBANDRY 

 FOUNDED ON REGULAR ROTATIONS ON DIF- 

 FERENT CROPS. ON pasture; VIEWS CON- 

 NECTED WITH ITS APPLICATION. ON VA- 

 RIOUS AGRICULTURAL OBJECTS CONNECT- 

 ED WITH CHEMISTRY. CONCLUSION. 



The improvement of steril lands by burning 

 was known to the Romans. It is mentioned by 



