388 



THE SOUTHERN PLANTER. 



[July 



Very similar to that of the salts of ammonia 

 and nitrate of soda ; but if we refer the ef- 

 fect of these last two substances to their ni- 

 trogen, because ammonia and nitric acid are 

 food for plants, then this explanation will 

 not hold good for common salt. For neither 

 this salt nor chlorine enters as an element 

 into the structure of plants, and it cannot be 

 asserted that either of themi is necessary, 

 although both are frequently met with as 

 constituents of the ashes of plants. 



The most recent observations on the com- 

 portment of the soil towards the food of 

 plants show how slight is the knowledge we 

 possess of their mode of nourishment, and 

 of the part which the soil, by its physical 

 condition, plays in it. The comportment of 

 the salts of ammonia, of chloride of sodium, 

 and of nitrate of soda, towards the earthy 

 phosphates in the soil, may perhaps assist us 

 in throwing some light on their action, or on 

 one of their actions, on the growth of plants. 



Like carbonic acid water, the sulphate, as 

 well as other soluble salts of ammoni i, pos- 

 sesses the property of rendering the earthy 

 phosphates soluble in water. 



We know of no other way in which the 

 earthy phosphates are dispersed through the 

 soil than by means of carbonic acid water. 

 If it is tt'ue that one of the chief effects of 

 humus, or the decaying remains of plants in 

 soils or in manures, consists in its forming a 

 source of carbonic acid, with which the air 



and water in the 



groun 



d is enriched : if it 



is also true that this carbonic acid water ren- 

 ders the earthy phosphates soluble, and thus 

 contributes to their distribution in the soil, 

 then there can be no doubt that the salts of 

 ammonia, which possess the same solvent 

 property, can in this respect repl. ce the or- 

 ganic matters, and thus exert an equally fa- 

 vourable influence on the growth of plants. 



The same solvent property is also possess- 

 ed among the salts of soda by Chili saltpe- 

 tre and common salt. It has been recently 

 shown that these two salts, even in the most 

 dilute solutions, dissolve earthy phosphates 

 to a very appreciable extent, and that con- 

 sequently they must play a part in the pro- 

 cess of the nutrition of plants, similar to that 

 which is ascribed to carbonic acid water (to 

 the humus) and to the salts of ammonia. 



From direct experiments it appears, that 

 220 lbs. of sulphate of ammonia in solution 

 in 9,900 galls, of water can dissolve 7.9 lbs. 

 of bibasic phosphate of lime (PO5, 2CaO, 

 aq.) such as exists in bones that have been 

 acted on by sulphuric acid ; or, in other 

 words, 100 lbs. of sulphate of ammonia in 

 4,500 gallons of water — dissolve nearly 4 

 lbs. of phosphate of lime. In like manner 

 123 lbs. of common salt, in 11,000 galls, of 

 water, dissolve 7i lbs. of bibasic phosphate 

 of lime ; and 220 lbs. of nitrate of soda, in 

 7,348 galls, of water, dissolve 5| lbs. of the 

 same phosphate. 



Tribasic phosphate of lime (PO5, 3CaO) 

 is much less soluble in these fluids. 



220 lbs. of 



In solution in water in 



Dissolve of tribasic phos- 

 phate of lime, PO5, 

 3 CaO. 



Sulphate of ammonia, 

 Common salt. 

 Nitrate of soda, - 



11,880 galls. 

 11,000 " 

 7,§26 



71 lbs. 



3i 



2.6 " 



The seeds of the cereals, particularly 

 wheat, contain phosphate of lime, and in 

 preponderating quantity phosphate of mag- 

 nesia. In many kinds of wheat the quanti- 

 ty of phosphate of magnesia is four times, 

 often ten times, greater than that of the 

 phosphate of lime ; and in like manner in 

 the grain of rye, oats, and barley, the mag- 



220 lbs. of 



In solution in water, in 



Dissolve of phosphate of 

 Magnesia, PO5 

 3 MgO. 



Nitrate of soda, 

 Common salt, 



73,260 lbs. 

 110,000 



4f lbs. 



8i " 



■ 



nesia salt exceeds very greatly the phosphate 

 of lime. These proportions are so constant 

 that they cannot be ignored in the cultiva- 

 tion of these plants. The comportment of 

 the salts above-mentioned towards phosphate 

 of magnesia and ammonia, and phosphate of 

 magnesia, appears, therefore of special in- 

 terest. 



