SALTS. 



SAMPLE. 



several wet days occur, the rain of the first 

 must contain more of it than the second. The 

 rain of a thunder-storm, after a long-protracted 

 drought, ought, for this reason, to contain the 

 greatest quantity which is conveyed to the 

 eartji at one time. But all the analyses of 

 atmospheric air hitherto made have failed to de- 

 monstrate the presence of ammonia, although, 

 according to our view (says M. Liebig), it can 

 never be absent. If a pound of rain-water con- 

 tains only one-fourth of a grain of ammonia, 

 then a field of 40,000 square feet must receive 

 annually upwards of 80 Ibs. of ammonia, or 65 

 Ihs. of nitrogen ; for, by the observations of 

 Schubler, which were formerly alluded to, 

 about 700,000 Ibs. of rain fell over this sur- 

 face in 4 months. This is much more nitro- 

 gen than is contained in the form of vegetable 

 albumen and gluten in 2650 Ibs. of woad, 2800 

 Ibs. of hay, or 200 cwt. of beet-root, which are 

 the yearly produce of such a field ; but it is 

 less than the straw, roots, and grain of corn 

 which might grow on the same surface would 

 contain. Experiments made in the laboratory 

 of Giessen, with the greatest care and exact- 

 ness, have placed (continues Liebig) the pre- 

 sence of ammonia in rain-water beyond all 

 doubt. It had hitherto escaped observation, 

 because no one thought of searching for it." 

 See AMMONIA. 



I cannot recommend the farmer to adopt the 

 able conclusions of M. Liebig without consider- 

 able caution : hardly any thing retards the pro- 

 gress of science more than erroneous theories. 

 Fortunately, however, the farmer can in all 

 cases patiently and successfully examine and 

 apply the valuable facts of the skilful chemist 

 without mystifying himself with not always in- 

 telligible doctrines. It is very probable thai 

 plants have the power of decomposing ammo- 

 nia, and of assimilating the nitrogen which it 

 contains, in the same way as there is little 

 doubt the hydrogen of water is assimilated by 

 them ; but we have no direct evidence of the 

 facts, and the best course, therefore, will be to 

 regard them not as absolute chemical truths, 

 but merely as of the class of what may be per- 

 haps denominated scientific probabilities. 



Some of the other compounds of chlorine, 

 the old class of chlorides of the chemist, have 

 been tried as fertilizers, with very doubtful 

 success ; for although at first the seeds which 

 had been steeped in them germinated with a 

 considerably increased rapidity, yet they speed- 

 ily seemed to suffer by this additional stimu- 

 lus. Davy tried solutions of chlorine, and sul- 

 phate of iron (green vitriol) : he says, "Though 

 the plume was very vigorous for a time, yet it 

 became at the end of a fortnight weak and 

 sickly, and at that period less vigorous in its 

 growth than the radish sprouts which had been 

 naturally developed, so that there can be 

 scarcely any useful application of these expe- 

 riments. Too rapid growth and premature de- 

 cay seem invariably connected in organized 

 structures, and it is only by following the slow 

 operations of natural causes that we are capa- 

 ble of making impovements." Oxymuriate 

 of lime, or, properly speaking, chloride of cal- 

 cium, however, appears to be beneficial to 

 vegetation : this was ascertained in 1796, by 

 978 



Ingenhouz ; and I have given in my work >n 

 Fertilizers, p. 367, the result of some trials by 

 Mr. Finchamwith this chloride that were highly 

 successful : he says, " Half of some turnip- 

 seed were steeped" for 36 hours in a solution 

 of chloride of calcium, composed of 1 part 

 chloride of calcium, and 48 parts water; this 

 was sown under precisely similar circum- 

 stances of soil and aspect with the other half 

 unsteeped. The first came up much sooner, 

 was never attacked by the fly, and the produce 

 was half as much again, and the tops made 

 more luxuriant. He attributes the failure of 

 Davy to his having used the chlorine, uncom- 

 bined with the base lime. Such then are the 

 chief facts with which I am acquainted, relating 

 to the uses of the saline bodies to vegetation. 

 It is a research much more extensive and 

 valuable than it at first may appear to the in- 

 telligent farmer. What we already know of 

 the action and (he effects of these saline bodies 

 as the food or constituents of plants, he will 

 find exceedingly important. It is more than 

 probable, that the salts act upon vegetation in 

 many beneficial ways, yet unknown to the phi- 

 losopher. The material action upon some soils 

 of saltpetre (nitrate of potash), for instance, is 

 to us inexplicable by any chemical knowledge 

 that we at present possess. The effect of cubic 

 petre and other salts is often equally mysteri- 

 ous ; but although there are difficulties of this 

 kind, the scientific farmer, far from allowing 

 such impediments to restrain either his ardour 

 or his thirst for knowledge, will only see in 

 these at present hidden truths additional rea- 

 sons for a noble perseverance in the pursuit of 

 knowledge ; for he will feel that the discovery 

 of the reasons of the at present many unknown 

 phenomena of vegetable life will in all reason- 

 able probability extend very materially the 

 powers, and increase the sphere of usefulness 

 of many succeeding generations of enlightened 

 cultivators. 



SALTPETRE (Germ, and Fr. salpetre). See 

 NITRATES and SALTS. 



SALTWORT (Salsola, from salsus, salt ; in 

 allusion to the saline properties of the species). 

 A genus of plants which inhabits the sea-coast, 

 especially abundant on the coast of the Medi- 

 terranean, where they are extensively gathered 

 and burnt for the manufacture of barilla and 

 soda. See KELP. 



SALT-MARSH CATERPILLAR. See CA- 



TEHPILLAH. 



SALVING or SMEARING sheep is resorted 

 to in various districts, for the purpose of pre- 

 serving the fleece from the effects of weather, 

 destroying injurious insects, and preventing 

 cutaneous diseases. A mixture of damaged 

 butter, hog's lard, resin, and Gallipoli oil, is 

 found to be the most efficacious salve. Tar 

 stains and spoils the colour of the wool. See 

 SHEEP. 



SAMPLE. A small quantity of a commodity 

 exhibited at public or private sales, as a speci- 

 men. Wool, wine, corn, seeds, and indeed 

 most species of agricultural produce and mer- 

 chandise that can be conveyed in small bulk, 

 are sold by sample. If an article be not at an 

 average equal to the sample by which it is 

 sold, the buyer may cancel the contract, aa" 



