1/2 gr. of HCl are necessary to form a gram 

 of KCl. Let us call these fractions, 3/4 and 

 1/2, the specific reactive weights of KOH 

 and HCl in respect to the formation of a 

 unit quantity of KCl. Suppose x amount 

 of KOH and y of HCl are given. If x and 

 y are divided by their respective specific 



4 

 reactive weights, we get - x and 2y. The 



o 



smaller of these quantities is a direct meas- 

 ure of the weight of KCl that can be 

 formed from x KOH and y HCl. If, for ex- 

 ample, X and y are both equal to three 

 grams, four grams of KCl can be obtained. 



These facts can be generalized. If A, B 

 and C are substances which react to form S 

 and M A, I) B and w C are necessary for the 

 formation of a unit amount of S, then u, v 

 and w may be called the specific reactive val- 

 ues of A, B and C, respectively. They may 

 be weights, volumes, numbers of molecules 

 or what not. In any particular ease, where 

 pA, qB and rC are reacting, the amount of 

 S formed is the smallest of the fractions 

 p/u, q/v, r/w. When the amounts of the 

 reacting substances are divided by their 

 specific reactive values, the smallest quan- 

 tity so obtained is equal to the amount of 

 the product formed. 



This conclusion is directly applicable to 

 the problem of fertilizers. It is known that 

 most of the higher plants must obtain 

 seven elements in combined form from the 

 soil. They are S, P, N, K, Ca, Mg and Fe. 

 If aS, /?P, yN, 8K, eCa, ^Mg and rjFe are 

 required for a unit amount of growth in 

 some particular plant, say wheat, and if 

 aS, &P, cN, dK, eCa, /Mg and grFe are pres- 

 ent in a particular soil in available form, 

 the maximum amount of wheat that can be 



