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THE POPULAR SCIENCE MOXTHLY.—SUPPLEMEXT. 



of grain. Albumen obtained from eggs is indeed 

 somewhat extensively applied by calico-printers 

 as a mordant for inducing cotton to take up col- 

 or?, especially the coal-tar dyes, in the same man- 

 ner as do silk and wool. Unfortunately, the al- 

 bumen of blood, which is highly improper as food, 

 has not yet been made available in all cases as a 

 substitute for egg-albumen, inasmuch as it has 

 not been practicably procurable in a colorless 

 state. Hence there is here room for a mordant 

 capable of " animalizing " vegetable tissues, and 

 yet involving no waste of human food. 



The use of wool in clothing does not involve 

 the loss of combined nitrogen which might be at 

 first suspected. The ultimate destination of the 

 dust from the shoddy-mill, and of the fibre itself 

 when no longer capable of being respun, is to 

 the manure-manufactory and to the fields. With 

 leather the case is less favorable. The raw hides 

 of animals, though probably worthless as the food 

 of man, are of great value as a nitrogenous ma- 

 nure; but after the tanning process they are 

 scarcely, if at all, available as plant-food. Leather- 

 waste will lie for years in the soil undecomposed, 

 and appears to exert no appreciable fertilizing in- 

 fluence. Hence a non-nitrogenous substitute for 

 leather would be a boon of no small magnitude to 

 the world. 



We have thus given a catalogue, by no means 

 exhaustive, of the operations and processes, in- 

 dustrial and domestic, by which nitrogen is 

 wasted. This waste, as we have seen, turns 

 mainly on its transformation from the combined 

 or solidified state to the free or gaseous condi- 

 tion, as it is found in the atmosphere. But in 

 this state, we shall be asked, is it not plentiful, 

 almost to infinity, and does there not exist here 

 one of those beautiful processes of circulation, of 

 which we often read, by which it is restored to 

 the combined or solidified state, and made again 

 available? Yes, the store of atmospheric nitro- 

 gen is all but infinite, and we dare not assert 

 that there is absolutely no natural process by 

 which it can be recombined with other elements ; 

 but these processes are slow in their operation, 

 and, as far as we can judge, they cannot keep 

 pace with our waste. They do not build up as 

 quickly as we can destroy. We know that the 

 atmosphere contains traces of ammonia, and that 

 nitric acid, in small quantity, may be detected in 

 rain, especially that which accompanies a thun- 

 der-storm ; but we are still doubtful how much of 

 this combined nitrogen has been really formed at 

 the expense of the inert atmospheric nitrogen, 

 and how much, on the other hand, is merely the 



decomposition of organic matter upon the earth's 

 surface. It is ascertained that the electric spark, 

 i. e., lightning, on passing through a mixture of 

 oxygen and nitrogen — in other words, through 

 common air — effects the combination of these 

 two elements, so as to form nitric acid. Water, 

 holding in solution atmospheric air, as do all nor- 

 mal waters on the earth's surface, is found to 

 yield nitric acid at the positive pole of the bat- 

 tery, and ammonia at the negative. Hydrogen 

 and nitrogen are also, according to the researches 

 of Donkin, induced to combine by the action of 

 the effluve, or silent electric discharge. But all 

 such processes, however varied, have been found 

 to be exceedingly slow in their action, and hence 

 incapable of practical application in the arts. 

 Ozone was once appealed to in every difficulty, 

 but it has been proved incapable of oxidizing free 

 nitrogen to nitric acid in presence of water, as 

 was suggested. Other reactions have been pro- 

 posed, but none of them has proved distinctly 

 and unequivocally successful as a means of com- 

 bining the free nitrogen of the air into ammonia, 

 or nitric acid, or cyanogen, or any other available 

 compound. To solve this, the king-problem of 

 practical chemistry, is a duty still unfulfilled, and 

 a triumph still unearned. It may again be urged 

 that processes which do not " pay," in our hands, 

 may yet prove successful in those of Nature, with 

 whom time is no object. If ammonia is but spar- 

 ingly manufactured in the upper regions of the 

 atmosphere, it may perhaps be evolved by the aid 

 of non-nitrogenous organic matter in some of the 

 phases of fermentation or of eremacausis. Or 

 the vital power of vegetables may solve the diffi- 

 culty : the growing plant may arrest atmospheric 

 nitrogen, and employ it in the formation of albu- 

 minoids. Method after method, thus pointed out 

 as possible, has been carefully scrutinized. In 

 most cases the experimental reply has been de- 

 cidedly negative, in a few equivocal, in none dis- 

 tinctly affirmative. It is undoubted that the at- 

 mosphere superincumbent upou an acre of ground 

 must supply combined nitrogen enough for all the 

 vegetation naturally growing upon this acre, and 

 must be able to keep up the supply from century 

 to century. Were this not the case, old Mother 

 Earth would long ago have lost her green, flower- 

 embroidered mantle. But, to grow the crops need- 

 ful for the support of our human population, we 

 are obliged to make, upon every single acre of 

 arable land, demands a hundred-fold greater than 

 Nature ever makes upon an acre of forest, or 

 prairie, or swamp, or moorland. 



As we have thus increased our requisitions, 



