230 



THE FARMER'S MAGAZINE. 



taken in order to determine the volume of water neces- 

 sary to irrigation in our climate during summer, I was 

 able easily to produce an absorption per hectare on land 

 strongly seeded with trefoil, ninety-seven cubic metres 

 of water every twenty-four hours. This was, after all, 

 not more than a watering to the extent of 9.07t. of 

 liquid per square metre. It was casting upon the soil 

 a covering of water of less than 0.01 in. thickness. 



Amongst the salts useful to vegetation conveyed by ir- 

 riiration to the soil, we ought to distinguish the nitrates, 

 the fertilizing effects of which had not escaped the saga- 

 city of M. Henri Sainte-Claire Deville in the classic 

 work he has published on the composition of potable 

 waters, and from which he has deduced as a consequence, 

 that the waters of springs and rivers are for meadows a 

 powerful manure by the silica and alkalies they bring 

 and by the organic substances and nitrates, in which 

 the plants find the azote indispensable to their organiza- 

 tion.* 



It is not necessary to insist upon the interest that 

 might be attached in detecting in the waters so active a 

 manure as saltpetre ; the results at which I have arrived, 

 by showing to what an extent the proportion of that 

 element varies, justify besides the opportunity of exe- 

 cuting similar researches. 



Thus I have scarcely been able to ascertain the nitrates 

 in those enormous masses of water contained in the 

 mountain lakes of the Vosges. 



The water of the Seven Lake with the same valley, a 

 little below Lake Stern, and from whence flows the 

 Dollar, has yielded per litre the equivalent of .07m. of 

 nitrate of potash. 



The pond at Soultzbach, near Woorth (Lower Rhine), 

 formed by the dam of the little river of Soultzbach, is 

 surrounded with mountains of sandstone of the Vosges. 

 In a litre there was but .03m. of nitrate. 



Spring Waters. — I have examined the waters of 

 fourieen springs. The poorest in nitre were those of 

 Liebfrauenberg, and of the ruins of Fleckenstein. Both 

 proceed from the sandstone of the Vosges, and the litre 

 contains from 0.03m. to 0.14m. of nitrate of potash. 



The spring waters in which I have found the most 

 saltpetre are those of the Ebersbronn (Lower Rhine), and 

 of Roppurtzwiller (Upper Rhine), which yielded re- 

 spectively 14 and 11 grammes of nitrate. These waters 

 are used for irrigation. 



Waters of Rivers. — Of the river waters analyzed the 

 least charged wiih saltpetre are those of the Seltz and 

 the Saiier, tributaries of the Rhine, which respectively 

 yielded 0.07m. to 0.08m. per cubic metre. 



Those which contained the largest proportion of ni- 

 trate are the Veste in Champagne, and the Seine ; the 

 water of the former holding 12 grammes, and that of the 

 Seine 9 grammes per cubic metre. This last result is 

 deduced from six determinations made between the 29th 

 of November, 1856, and the 18th of January, 1857. 

 In 1846 M. H. Sainte-Claire Deville detected in the 

 water of the Seine, in nitrate of soda and magnesia, the 



* Annates de Chimie et de physique, 3rd Series, v. 23, p. 52. 

 The following is the summary of the labours of M. Sainte- 

 Claire Deville. "These analyses eatablish, Ist. Ttie im- 

 portance of the portion of silica in potable waters, which M. 

 Payen had previously found in great quantity in the water of 

 the wells of Grenelle. 2ad. The part which this agent, in 

 connexion with the azoteous matters of the waters, takes in 

 the fertilization of meadows. 3rd. The sinniar part which we 

 ought to ascribe to nitrates in the action of water as manure, 

 and consequently the importance of the nitrous elements in 

 mauycases. (1.) Water taken the 22nd October 1856. Inien- 

 tion the dates, because in the waters, as in the earths, the pro- 

 portion of nitrates is not at all periods the same. (2.) Water 

 taken the 25th October, 1856. (8.) Water taken the 24th 

 Auf<uat, 1866. 



equivalent of 1 8 grammes of nitrate of potash per cubic 

 metre. 



At low water the Seine delivers at Paris per second 

 75 cubic metres, and during the average waters 250 cubic 

 metres. In adopting 9 grammes for the nitrate, we find 

 that at low water, in 24 hours, the stream carries to the 

 sea the equivalent of 58,000 kilos, of nitrate of potash, 

 and the medium waters 194,000 kilos. 



If, now, we consider that the volume of waters of the 

 Seine is far inferior to that of the generality of the large 

 streams which furrow the different continents, we shall 

 comprehend how immense is the mass of saltpetre con- 

 tinually borne away to the hydrographic basins ; and 

 with what incessant activity the phenomena which deter- 

 mine the nitriiication must act on the surface of the 



Water of Wells, — I have generally found more ni- 

 trates in wells sunk in villages and rural workings than 

 in springs and rivers ; but here again the proportions 

 have been most variable. For example, the water from 

 the well of Bechelbronn, which indeed is not exempt 

 from some traces of oil of petrolium, contains only indi- 

 cations of nitrates; whilst the water of the wells of 

 Woerth and Freischwiller (Lower Rhine), sunk in the 

 lias marl, exhibit from 66 to 94 grammes per cubic 

 metre. But it is in the wells of the great cities that we 

 find the largest quantities of nitrate. This fact has long 

 since been known, and M. Henri Sainte-Chire Deville 

 has found in water raised at Besancjon the equivalent of 

 198 grammes of nitrate of potash per cubic metre. The 

 proportion of nitre that I have met with, in the waters 

 proceeding from 40 wells selected in the twelve arron- 

 dissements of Paris, is still larger. The experiments have 

 been executed by two processes which I have employed 

 comparatively — the decoloration of indigo, and the in- 

 genious method we owe to M. Pelouze. The well waters 

 in which there was the least nitrate came from the fol- 

 lowing places ; — 



Nitrate of 

 Potash. 

 Rue Guerin-Boiaseao, in which we detected per 



cubic metre the equivalent of 200 gr. 



Rue Saint Martin 225 



Rue Samte Georges 238 



Rue des Petites-Ecuries 258 



The waters which have yielded the most nitrate were 

 those from the wells in the most ancient quarters. In 

 the water of a well in 

 Rue du Fouarre, we found per cubic metre the 



equivalent of 1,031 gr. 



Rue du Foiu Saint- Jacques 1,500 



Rue Saint-Landry 2,093 



Rue Traversiue 2,165 



In two wells on the grounds of market gardeners in 

 the Faubourgs, the cubic metre of water contained 

 1.268 k. and 1.546 k. of nitrate. It is thus seen that 

 100 cubic metres of these waters, exclusively destined 

 for watering the grounds, convey to them from 120 to 

 125 kilos, of saltpetre, the utility of which as a fertilizer 

 cannot be disputed, especiall)- when we know that in 

 summer a hectare of market-garden ground absorbs from 

 30 to 40 cubic metres of water per day. 



The large proportion of nitrate found in the water of 

 the wells of the capital is undoubtedly due to the modi- 

 fications to which the organic matters with which the 

 soil is constantly impregnated are subject. The purity 

 of the air and the water, the effects of which manifest 

 themselves so powerfully upon the public health, must 

 be deeply affected with it. I have shown at another 

 period that the rain, after having swept, in crossing, the 

 atmosphere of a large city, holds in solution or in sus- 

 pension much more ammoniacal and putrescent organic 

 principles than when it falls at a distance in the country. 

 To-day I have shown that the water of wells, after being 



