)S3s] 



FARMERS' REGISTER. 



627 



of coarse fiiliceous sand; and Ihe finely divided 

 matter ronsi^ied of 

 7 Aluniinfi. 

 14 Silica. 



63 Carhoiinte of lime. 

 2 Oxidn of iron. 



14 Vcirei;il)Ie, animal, and saline matter. 

 In all these instances the lertiliiy seems to de- 

 pend upon the state nfdivisron, and mixture ol'the 

 ^aithy materials and the veiretablR and animal 

 tnattcr; and may be easily explained on the prin- 

 ^ciples which I have endeavored to elucidate in the 

 precediniT part oCthis Lecture. 



In ascerraininrr the composition of steril soils 

 \vith a view to their improvement, any particular 

 ^ngredienl; which is the cause of their unproduc- 

 tiveness, should he particularly attended to ; if pos- 

 sible, they should be compared with fertile soils in 

 the same neiirhborhood, and in similar situations, 

 Bs the difference of the composition may, in many 

 cases, indicate the most proper methods of im- 

 ■provement. I/on washing a steril soil it is (bund to 

 xjontain the salt of iron, or any acid matter, it may 

 he ameliorated by the application of quick-lime. 

 A soil ofsood apparent texture from Lincolnshire, 

 ■was put into my hands by Sir Joseph Banks as 

 remarkable for .sterility. On examininjr it, I found 

 that it contained sulphate of iron : and I offered 

 the obvious remedy of top-dressing with lime, 

 which converts the sulphate into a manure If 

 •there be an excess of calcareous matter in the soil, 

 it may be improved bv tlie application of sand, or 

 flay. Soils too abundant in sand are benefited by 

 ^he use of clay or marl, or vecretable matter. A 

 field belongincj to Sir Robert Vauo;han at Nannau, 

 iMerionelhshire, the soil ofwhich wasa lightsand, 

 was much burnt up in the summer of 1805 ; I re- 

 commended to that (jentleman the application of 

 peat as a top-dressinrr. The experiment was at- 

 tended with immediate fjood effects ; and Sir Ro- , 

 •bert has informed me, that the benefit was perma- 

 nent. A deficiency of vecetable or animal mat- ! 

 ter must be supplied by manure. An excess of 

 vegetable matter is to be removed by burninir, or 

 to be remedied by the application of earthy mate- 

 rials. The improvement of peats, or bogs, or marsh 

 Jands, must be preceded by draining; stagnant 

 'water being injurious to all the nutritive classes* of 

 plants. Soft black peals, when drained, are often 

 made protluctive by the mere application of sand 

 or clay as atop-dressing. When peats are acid, 

 or contain ferruginous salts, calcareous matter is 

 absolutely necessary in bringing them into cultiva- 

 tion. When they abound in the branches and j 

 ■roots of frees, or when their surface entirely con- 

 sists of living vegetables, the wood or the vegeta- ! 

 bles must either be carried off, or be destroyed by ! 

 burning. In the last case their ashes afford earthy j 

 ingredients, fitted to improve the texture of the I 

 peat. 



The best natural soils are those of which the i 

 materials have been derived from different strata; j 

 which have been minutely divided by air and wa- 

 ter, and are intunalely blended together : and in 

 improving .^joils artificially, the farmer cannot do 

 better than imitate the processes of nature. ! 



The materials necessary for the purpose are sel- j 

 dom far distant : coarse sand is often found imme- 

 diately on chalk ; and beds of sand and gravel are 

 common below clay. The labor of improving the 

 texture or constitution of the soil is repaid by y 



great permanent advantage; less manure is re- 

 quired, and its fertility insured. And capital laid 

 out in this waj' secures for ever 'he productiveness, 

 and consequently the value, of the land. 



LECTURE V. 



ON THE NATUUE AND CONSTITUTION OK TIIK 

 ATMOSPHERE, ANIJ ITS INFLUENCE ON VE- 

 GETABLES. OF THE GERMINATION OF 

 SEEDS. OF THE FUNCTIONS OF PLANTS IN 

 THEIR DIFFERENT STAGES OP GROWTH; 

 WITH A GENERAL VIEW OP THE PROGRESS 

 OF VEGETATION. 



The constitution of the atmosphere has been 

 already generally referred to in the preceding 

 Lectures. Water, carbonic acid gas, oxygen, and 

 azote, have been mentioned as the principal sub- 

 stances composing it; but more minute inquiries 

 respecting their nature and agencies are necessary 

 to afford correct views of the uses of the atmo- 

 sphere in vegetation. 



On these inquiries I now propose to enter; the 

 pursuit of them, I hope, will offer some objects of 

 practical use in farming; and present some philo- 

 sophical illustrations ol'the manner in which plants 

 are nourished, their organs unfolded, and their 

 functions developed. 



If some of the salt called muriate of lime that 

 has been just heated red be exposed to the air, 

 even in the driest and coldest weather, it will in- 

 crease in weight and become moist ; and in a cer- 

 tain time will be converted into a fluid. If put 

 into a retort and heated, it will yield pure water; 

 will gradually recover its pristine state; and, if" 

 heated red, its former weight : so that it is evident 

 that the water united to it was derived from the 

 air. And that it existed in the air in an invisible 

 and elastic form, is proved by the circumstance, 

 that if a given quantity of air be exposed to the 

 salt, its volume and weight will diminish, provided 

 the experiment be correctly made. 



The quantity of water which exists in air, as 

 vapor, varies with the temperature. In propor- 

 tion as the weather is hotter, the quantity is great- 

 er. At 50° of Fahrenheit air contains about -g\ of 

 its volume of vapor; and as the specific gravity of 

 vapor is to that of air nearly as 10 to 15, this is 

 about ,V of its weight. 



At 100°, supposino: that there is a free commu- 

 nication with wafer, it contains about yV parts in 

 volume, or ^V in weight. It is the condensation 

 of vapor by diminution of the tem.perature of the 

 atmosphere, which is probably the principal cause 

 of the formation of clouds, and of the deposition 

 of dew, mist, snow, or hail. 



The power of different substances to absorb 

 aqueous vapor from the atmosphere by cohesive 

 attraction was discussed in the last Lecture. The 

 leaves of living plants appear to act upon the va- 

 por likewise in its elastic Ibrm, and to absorb it. 

 Some vegetables increase in weight ti-om this caupe, 

 when suspended in the atmosphere and uncon- 

 nected with the soil ; such are the houseleek, and 

 different species of the aloe. In very intense hea^a, 

 and when the s-oil if. dry, the life of plante seemt; 

 to be preserved by the absorbent power of thf ir 

 leaves : and it is a beaut tJiil circumstances in the 



