1853.] 



EXTRACTS FROM EXHIBITION LECTURES. 



135 



the same kind of timber is seen as that wliich occupies the 

 adjacent forest. 



This carries iis back through a period of at least 600, and pro- 

 bably of 1000 years, as the limit within which this counti-y has 

 not been occupied either by tlie old cojiper-diggers or tlie race of 

 the mounds. We have historical evidence from the Spaniards 

 that North America was occupied by the Aboiigines three 

 hundi'ed and sixty, and from the Icelanders eight hundred and 

 fifty one years ago. If they came as emigrants from Mongolian 

 tribes of Asia, a long period must have elapsed after their ari-ival 

 in order to allow of such an increase of their numbers. 



The natural increase of civilized nations is much greater than 

 of barbarous ones; and in the former case it does not exceed 100 

 per cent, in 40 years. The Mongolians may have passed freely 

 from Asia to America, as the " Esquimaux ",or Eskimo do now 

 m their " kinks," made of skins ; bnt there is no apparent reason 

 for an emigration more rapid than the surplus population would 

 djmand. Upon the whole, it seems that it must be since the 

 Aztecs left, and the Indians assumed the middle States of the 

 West, from 1500 to 2000 years. 



A long period must have elapsed between the first appearance 

 of the Aztecs upon our soil and their exodus to the South, during 

 which the copper mines were wj-ought, the mounds, earth-works, 

 and fortifications built, and the rich lands of the Western States 

 cultivated. If we add one thousand years for their occupation of 

 the Northern States, it does not carry us back beyond the founda- 

 tion of Rome [753 years B.C.]; and when Rome was built the 

 ruins of Pa;stum were so ancient that no one knew, fiom history 

 or tradition, the peojile who erected those fallen structures. 



Cleveland, August, 1852. 



Extracts from ExhibiliGH Lectuies. 



Iron Smelting. — Let us select the smelting of iron as an 

 example of the teachings of Chemistry. If practice, unaided by 

 Science, be sufficient for the prosecution of manufactures, this 

 venerable art must be thoroughly matured, and Science could 

 scarcely expect to be of much use to it in its present state. But 

 ■while we find much to admire in the triumphs of practical Expe- 

 rience, there is yet great room for the improvement of this art. 

 The cheapness of ii-on ore, and of the coal used in its smelting, 

 has been so great, that, regardless of t'leir capital importance to 

 tl is country, we, like careless _ spendthrifts, use them without 

 thought of the future. 



The mode of smelting iron consists in mixing the ore with 

 lime and coal, the former producing a slag or glass with the im- 

 purities of the ore, while the coal reduces the oxide of iron to its 

 metallic state. Much heat is required in the process of smelting, 

 but the cold air blown in, as the blast, lowers the temperature, 

 and compels the addition of fuel, as a compansation for this re- 

 duction. Science pointed to this loss, and now the air is heated 

 before being introduced to the furnace. The quantity of coal is 

 wonderfully economized by this application of Science ; for, in- 

 stead of seven tons of coal per ton of iron, three tons now suffice, 

 and the amount produced in the same time is increased nearly 

 .sixtj' per cent. Assuredly this was a great step in advance. 

 Could Science do more ? 



Professor Bunsen, in an inquiry in which I was glad to afford 

 him aid, has shown that she can. We examined the furnaces, in 

 each portion of the burning mass, so as fully to expose the opera- 

 tions in every part of the blazing structure. This seemingly im- 

 possible dissection was accomplished by the simplest means. The 

 furnacts are charged from the top, and the materials gradually 



descend to the bottom ; with the upper charge a long graduated 

 tube was allowed to descend, and tne giises streaming trom ascer- 

 tained depths were collected and analyzed. Their composition 

 betrayed with perfect accuracy the nature of the actions at each 

 portion of the furnace ; and the astonishing fact was elicited that, 

 in spite of the saving produced by the hot blast, no less than 81-^ 

 per cent, of fuel is actually lost, only IS^-per cent, being realized. 

 Itj in round numbere, we suppose that four-fifths of the fuel be 

 thus wasted, no less than 5,400,000 tons are every year thrown 

 uselessly into the atmosphere, this being nearly one-seventh of 

 the whole coal annually raised in the United Kingdom. This 

 enormous amount of fuel escapes in the form of cumbustible 

 gases, capable of being collected and economized; yet, in spite of 

 these well-ascertained fiicts, there are scaicely half-a-dozen fur- 

 naces in the United Kingdom where this economy is reahzed by 

 the utilization of the waste gases of the furnace. 



Large quantities of ammonia are annually lost in iron-smelting, 

 which might readily be collected. Ammonia is constantly 

 increasing in value, and each fui'nace produces and wastes at the 

 least 1 cwt. of its principal salt daily, equivalent to a considerable 

 money loss. With the low price of iron, this subsidiary product 

 is worthy of attention. As I write, a Welsh smelter has visited 

 me, to say that he has adopted this suggestion with advantageous 

 results. I might adduce other improvements introduced by 

 Chemistry in the smelting process; but these will suffice to show 

 you that she has atlded to human power by increasing produc- 

 tion, while she has also economized both the time and the 

 materials employed. 



Textile Fabrics. — Without the aid of Chemistry, it would 

 ha\e been impossible for textile fabrics to have attained their 

 present development. The bleaching of cotton and linen was not 

 much practised in England until about a century since; before 

 that time they were sent to Holland, where the operation of 

 bleaching consisted in steeping them in potash for a few days, 

 afterwards for a week in buttermilk, and then exposing them for 

 several months on a meadow to the influence of the sun and 

 moisture. A great improvement was made in Scotland by sub- 

 stituting sulphuric acid for sour milk ; and the immediate effect 

 was to reduce the time from eight to four months. In 1785, a 

 French Chemist suggested the use of chlorine as a means of 

 hastening the process ; and in the hist year of the eighteenth 

 century a compound of this gas with lime was introduced by 

 Tennant of Glasgow. The de\'elopment of the cotton manufac- 

 ture now became immense. By a happy adaptation of other 

 chemical processes, in conjunction with the bleaching power of 

 chlorine, the time required for the whitening of cotton and linen 

 fabrics was at once reduced from months to hours, while the miles 

 of outstretched calico, defacing the verdure of country districts, 

 disappeared, the whole operation being carried on within the 

 small space of an ordinary factory. You may imagine what an 

 impulse this gave to a trade so important to us. The bleaching 

 of calico now consists of a chemical operation of great precision ; 

 that of silk and wool has not yet been so thoroughly compre- 

 hended by Science, and consequently has not deri\ed so many 

 advantages from its application. 



A greater acquaintance with the theory of bleaching has led 

 to a better understanding of the very ancient practice of washing. 

 The washing of domestic linen is by no means an operation too 

 insignificant for the attention of' the Chemist. A dozen shirts 

 may cost 3/. 12s., this being the united interest of the producer, 

 cotton-spinner, and shirt-maker. These shirts will last three 

 yeai-s, with care ; and supposing three to be washed each week, 

 the cost of washing — that is, the washerwoman's interest in the 

 dozen shirts — amounts to 7Z.16s.,or more than double that of the 

 cotton-spinner. In fact, the cost of washing is about one-twelftli 



