:30 DESTEUCTIVENESS OF MAN. 



without producing or requiring any important change in the nat- 

 ural arrangements of surface or in each other's spontaneous tend- 

 encies, except such mutual repression of excessive increase as 

 may prevent the extirpation of one species by the encroachments 



ture — not to speak of older and more familiar applications — besides being 

 highly remunerative, has better secured the harvests, and it is computed thaT- 

 the 230,000 threshing machines used in the United States in 1870 obtained five 

 per cent, more grain from the sheaves which passed through them than could 

 have been secured by the use of the flail. 



We are also beginning to learn a better economy in dealing with the inor- 

 ganic world. The utilization — or, as the Germans more happily call it, the 

 Verwerthung, the bewortMng — of waste from metallurgical, chemical and 

 manufacturing establishments, is among the most important results of the 

 application of science to industrial purposes. The incidental products from 

 the laboratories of manufacturing chemists often become more valuable than 

 those for the preparation of which they were erected. The slags from sUver 

 refineries, and even from smelting houses of the coarser metals, have not un- 

 frequently yielded to a second operator a better return than the first had de- 

 rived from dealing with the natural ore ; and the saving of lead carried off in 

 the smoke of furnaces has, of itself, given a large profit on the capital invested 

 in the works. According to Tire's Dictionary of Arts, see vol. ii., p. 832, an 

 English miner has constructed flues five miles in length for the condensation 

 of the smoke from his lead-works, and makes thereby an annual saving of 

 metal to the value of ten thousand pounds sterling. A few years ago, an 

 officer of an American mint was charged with embezzling gold committed to 

 him for coinage. He insisted, in his defence, that much of the metal was 

 volatilized and lost in refining and melting, and upon scraping the chimneys 

 of the melting furnaces and the roofs of the adjacent houses, gold enough was 

 found in the soot to account for no small part of the deficiency. 



It is f amiharly known that the sweepings of gold and silver smiths' shops 

 have a regular market value. It is worth noticing that the "sweep" of the 

 British mint in 1873 yielded L. 2,995, 8, 3. 



There are still, however, cases of enormous waste in many mineral and me- 

 chanical industries. Thus, while in many European countries common salt is 

 a government monopoly, and consequently so dear that the poor do not use as 

 much of it as health requires, in others, as in Transylvania, where it is quar- 

 ried like stone, the large blocks only are saved, the fragments, to the amount 

 of millions of hundredweights, being thrown away. — Boner, Transylvania, 

 p. 455, 6. 



One of the most interesting and important branches of economy at the pres- 

 ent day is the recovery of agents such as ammonia and others which had been 

 utilized in chemical manufactures, and re-employed them indefinitely after 

 wards in repeating the same process. 



Among the supplemental exhibitions which will be formed in connection 

 with the Vienna Universal Exhibition is to be one showing what steps have been 



