Sept. 19, 1884.] 



♦ KNOWLEDGE -> 



237 



exhibited not long ago might find employment, hut — not 

 to speak of difficulties in getting it to work on the right 

 spot — it is sufficient to observe that two French lumber- 

 men, each with a good axe, will fell a spruce, 2 ft. in dia- 

 meter in ten miuutes. It is likely to be a long time before 

 machinery can compete with hand labour of such quality 

 and on such work. The trees — with the exception of 

 saplings G in. in diameter and less, which are cut even with 

 the giound — are hewn down, so as to leave stumps about 

 3 ft. high, which form very unsiglitly objects in all new 

 clearings. The reason for this will appear shortly. The 

 trees so felled — unless burnt as they lie, which was often 

 the practice in early days — are hauled off the ground by 

 gangs of lumbermen — "teamsters," earning 40 dols. a 

 month — and taken to the saw-mill, or brought down to 

 the nearest river, and launched in vast rafts down the 

 stream to cities and civilisation. This takes place, of 

 course, in the winter, and as soon as spring has fairly 

 set in, the preliminary operations are completed by 

 setting fire to the weeds, scrubs, saplings, &c., and reducing 

 the whole, together with the larger stumps, to charred frag- 

 ments and ashes. The ground is then immediately sown, 

 as it best may, with wheat, and grass seed is scattered in 

 at the same time. The wheat is cut in the "fall," generally 

 yielding a fair crop ; the stubble is crushed down by the 

 snow in the winter, and the grass springs up in the 

 following spring. After three or four crops of hay have 

 been got, the ground becomes " pasture," and is browsed 

 by cattle for a space of some five or six years more. By 

 this time the smaller stumps are rotten, and can be drawn 

 out of the ground by a team of horses or oxen. Between 

 the large stumps which still remain it is possible to plough, 

 and the ground may now be brought into ordinary cultiva- 

 tion, generally on the four-course system. In three or 

 four years more the large stumps are amenable to the 

 same treatment. They are drawn accordingly, with more 

 or less difficulty, and the last vestige of the primeval bush 

 has disappeared. 



Now, in the whole of the above operations it is obvious 

 there is very little which can claim the aid of the engineer. 

 Even ordinary agricultural implements — reapers or ploughs 

 — are hardly applicable so long as the stumps remain to 

 cumber the ground. It is true that, as I was told, a san- 

 guine Scotchman, some years ago, proposed to use traction 

 engines for the purpose of drawing these stumps, without 

 waiting for their decay. He even induced people to rind 

 money for the purpose — for what purpose will not people 

 find money, if it be only absurd enough ? — but the prac- 

 tical results were as might have been expected. Stumps 

 are, as a matter of fact, often raised by means of screw 

 tackle, mounted on a strong waggon bed, and worked by 

 horses ; but this is a very rude affair, needing nothing in 

 the way of expensive machinery. Even when the last 

 stump is drawn, and the land has got into the full swing 

 of cultivation, although the resources of modern agricul- 

 tural engineering may be brought into play, it is not from 

 Great Britain that they will be drawn. Canadian farmers 

 will have nothing to do with English implements, which 

 they consider altogether too heavy and unsuited for their 

 work. They prefer the lighter, cheaper, and handier 

 machines made in their own country or in the United 

 States ; and if you urge the cost of repairs, they reply that 

 almost all the pai-ts being in duplicate, there is very little 

 difficulty in replacing them. The same applies to the saws 

 and wood-working machinery as required for the lumber 

 trade ; while in general engineering the differences in prac- 

 tice between the two countries are sufficient in almost aU 

 cases to determine the choice. 



{To he continued.) 



ELECTRO-PLATIXG. 



By W. Slingo. 

 XL 



LET us now turn our attention to the deposition of 

 copper upon iron, kc. Very many interesting and 

 pleasing effects may be produced in this way, more espe- 

 cially if the copper film is subsequently coated with another 

 of one of the more precious metals — gold or silver. 



The iron must not be placed directly into the bath, 

 otherwise the deposit will only occur in places, if at all 

 The surface of an iron object is never chemically clean, 

 hence the necessity for the preliminary treatment. A par- 

 ticle of grease is highly pernicious, but is easily removable. 

 This is accomplished by washing in a strong caustic alkali 

 solution, consisting of sodic or potassic hydrate (caustic 

 soda or caustic potash), dissolved in water, with the addition 

 of a little fresh slaked lime. After remaining in the clear 

 solution for some time, the iron object is removed, and well 

 washed with clean water. The iron surface has besides a 

 more or less copious supply of other foreign matter, which 

 is removed by placing in a vitriol solution made by mixing 

 together a pound of sulphuric acid and a gallon and a half 

 of water, adding two or three ounces of hydrochloric acid 

 to remove the more obstinate impurities. It will be found 

 that this " pickle " will remove all the injurious matter 

 likely to be met with. Were we to immerse in the bath an 

 impure surface, the probability is that local action would 

 ensue, considerably to the detriment of the deposit. After 

 remaining in the pickle for some little time the iron is re- 

 moved and well scrubbed with sand and water. Any 

 foreign particles that may have been loosened, but not re- 

 moved by the acid, are thus torn away and a good surface 

 results. The student might, by way of experiment, prove 

 the effect of an imperfect surface, using a small iron object, 

 such as an old key, in a small quantity of solution. This 

 solution should, however, be subsequently thrown away. 



The object to be coated is then attached to the negative 

 electrode, and placed in the bath. The solution differs 

 from that used to precipitate copper upon a plumbago or 

 suver surface. Two ounces of sulphate of copper are dis- 

 solved in boiling soft water, and after allowing to cool, foui 

 ounces of carbonate of potash are added, and two or three 

 ounces of strong ammonia solution. After a time, about 

 six ounces of cyanide of potassium are gradually added, untU 

 the blue colour disappears. It is anticipated that some 

 difficulty will be experienced in procuring the cyanide, in 

 consequence of its highly poisonous properties, but it may 

 be obtained in the same way that other poisons are pro- 

 curable. After allowing to stand for some time, the clear 

 solution is poured off, the precipitate which has formed 

 being left behind. 



The object is kept in the solution until a thin but perfect 

 deposit is obtained, when it is removed and placed in the 

 acid solution employed in previous experiments. The 

 reason for this is that in acid solutions, iron, zinc, and 

 other metals are assailable, whence the use of the cyanide 

 solution. When, however, a thin deposit has been pro- 

 cured, there is no longer any necessity to use the cyanide 

 solution, as the object is to all intents and purposes a 

 copper one. It is noticeable that, iron being a good con- 

 ducting metal, the resistance of the object is very much 

 less than that offered by a substance of a non-conducting 

 nature, coated with plumbago or any other conducting 

 material 



Other solutions might be used, but the above appears to 

 be the best, and answers very well. 



Hitherto a pitch-lined wooden bath has answered all 



