THE FARMERS' REGISTER. 



195 



too full of impurities, to be useless for the pur- 

 noses of irri^mion. 



1 propose in this paper to inves'igale the chemi- 

 cal pro leriies ol' river waier, and of the eHecis 

 produced t.y it in irricration, adding a few rernarks 

 upon the practice of the best and most slullnl 

 cnhivatorsol' ihe water-meadows oi the south o, 



England. . . ^ . 



1, Wiih regard to the composition ol river 

 water, there have heen several chemical examina- 

 tions :' that ol the Thames was analyzed by Dr. 

 Bostock, who found, in 10,000 parts alter most ol 

 iis mechanically suspended matters had subsided, 

 about li pans of loreign substances, viz.— 



Part?. 



Organic matters . - - 0.07 



Carbonate of lime - - - 1.53 



Sulphate of lime - - - 0-15 



Muriate of soda ... 0.02 

 In an equal quantity of the waters of the Clyde, 



Dr. Thomson found 1^ part ol' solid substances, 



namely, — 



Parts. 

 Common salt - - - 0.369 



Muriate of magnesia - - 0.305 

 Sulphate of soda - - - 0.114 

 Carbonate of lime - - - 0.394 



Silica 0.118 



The water of the Itchen in Hampshire is one ol 

 the most celebrated of all the southern streams, 

 for the use of Ihe irrigator. I (ound in 10,000 

 pans of its water, about 2| parts of solid matter, 

 viz : — 



Parts. 



Organic matter . - - 0.02 

 Carbonate o( lime . - - 1,89 

 Sulphate of lime - - - 0.72 

 Muriate of soda - - - 0.01 

 From an examination of the substances found in 

 these streams and they afiord a pretty correct 

 view of the contents ol mo:~t others, the larmer 

 will see that they all yield ingredients which are 

 the food or natural constituents of the grasses. 

 Thus, sulphate and carbonate of lime are Ibund 

 in most of them, and there is no river water which 

 does not contain, in some proportion or other, or- 

 ganic matter. To ascertain, therefore, whether 

 pure water was alone able to effect all tlie magic ef- 

 iects of irrigation, it was necessary to employ other 

 water than that of rivers, lakes, or even springs. 

 Pure water, as obtained by distillation, there- 

 fore, has been tried as a supporter of vegetation, 

 but it waslound totally inad_equale to the support of 

 plants, — they merely vegetated lor a time, but they 

 could not, by any means, be made to perlect their 

 BPeds. In this conclusion, the experiments of 

 Dr. Thomson, and of MM. Saussure and Hassen- 

 I'ratz, entirely agree. Pure water, therelore, not- 

 withstanding the dreams ol the Greek philosophers, 

 and the celebrated deceptive experiments of Van 

 Helmont with his willow tree, is not able to sup- 

 port the growth of the grasses. Van Helmoni's 

 tree, when he planted it in anearthern pot, weigh- 

 ed five pounds; the earth previously dried in an 

 oven, weished 200 pounds; after five years it 

 weighed 164 lbs., although it had been watered 

 during that time with only rain and distilled 

 water, and the earth had lost only two ounces in 

 weight. Hence, said Van Helmont and his disci- 

 ples, water is the sole food of plants. Bergman, 



in 1773, first pointed out the source of error. He 

 showed, from the experiments of Margraft", that 

 the rain-waler contained a suflioieni quantity of 

 earth to account for tl,e increased weight in the 

 willow, every pint of rain-water containing one 

 crrain of earth. Then, again, the earthen vessel 

 (which was sunk in the earth) would in this expe- 

 riment transmit its moisture impregnated with ail 

 kinds of soluble substances. And yet, it has been 

 shown, that impure water, such as that from a 

 sewer or Irom a dunghill, is alone sufficient to sus- 

 tain vegetation. This was clearly evidenced in 

 the experiments of M. Lampadius ; for he found, 

 that plants placed in a pure earth, such as silica 

 or alumina, although they would not grow when 

 watered with pure water only, yet, when watered 

 wiih the liquid drainage of a dunghill, they 

 flourished very luxuriantly, and this fact has been 

 also proved in another way. It has been shown 

 by chemical analysis, that the quantify of solid or 

 earthy matters absorbed by plants, is in exact pro- 

 portion to the impurity of the water with which 

 they are nourislied. Thus, equal quantities of 

 some plants of beaor, led by distilled water, 



yielded 



Parts. 

 Of solid matters or ashes - - - 3.9 

 Those led by rain-water - - - 7.5 

 Those grown in garden mould - - 12.0 

 These facts strongly confirm the conclusions of 

 some of the most sagacious cultivators, that the 

 chief advantages of irrigations are attributable to 

 the foreign substances with which the water is 

 charged,°although, as [ have elsewhere observed, 

 almost every farmer has a mode of accounting lor 

 the highly lertilizing effects of irrigation— one 

 thinks it cools the land, another that iT keeps ilie 

 crrass warm in winter. And this was Davy's opi- 

 nion. He thought that a winter flooding protected 

 the grass Irom the injurious efi'ects of I'rosf. He 

 says, " Water is ofgreater specific gravity at 42 

 deg. that at 32 deg.— the Ireezing point ; and 

 hence, in a meadow irrigated in winter, the water 

 immediately in contact with the grass is rarely 

 below 40 deg., a degree of temperature not at all 

 prejudicial to the living organs of plants. In 1804, 

 in the monih of March, I examined the tempera- 

 ture in a water meadow near Hungerford in Berk- 

 shire, by a very delicate thermometer. Tiie tem- 

 perature of the air at seven in the morning, was 

 43 des- In general, those waters which breed the 

 best fish are the best fitted for watering meadows, 

 but most of the benefits of irrigation may be de- 

 rived from any kind of water." 



Such were "the opinions of Davy as to the fer- 

 tilizing properties of water. It is to be regretted 

 that the opportunities for agricultural observations 

 of this great chemical philosopher were so Cew, 

 for his valuable remarks were always cautiously 

 made. He appears, however, as I have remarked 

 elsewhere, never to have steadily investigated the 

 chemical composition of river-water with regard 

 to its uses in irrigation, and, in consequence, knew 

 little of the value of some of its impurities to ve- 

 getation. Thus, if the river water contains gyp- 

 sum (sulphate of lime,) which it certainly does — 

 if the water is hard, it must, under ordinary cir- 

 cumstances, on this account alone be highly fer- 

 tilizing to meadows, since all grasses contain this 

 salt in very sensible proportions ; for, calculating 

 that one part of sulphate of lime is contained io 



