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Grass Valley, September 29, 1851
SCIENCE is progressive. The wonderful development of the power of steam by Fulton was only the prelude to vast and material improvement, until it has at length reached the perfection exhibited at the present day. It is so in mechanics--it is the same in astronomy, in geology; it will be so in mining and its modus operandi. On the first discovery of gold in the placers of California, the first mode of washing was by the pan; then a rough rocker was substituted, which was subsequently much improved, and quicksilver introduced. This was succeeded by the Long Tom and then by the sluice, by which it was found that dirt which would not pay by the pan or rocker yielded a handsome profit, and ground which had been passed over as worthless was found to contain gold in such quantities that fortunes were made. When the first quartz veins were worked the specimens, or those pieces in which gold was visible only, were saved, and these were pounded out by hand, until by repeated experiments and the introduction of machinery it was found that much of the rock which had been discarded was really rich and contained gold enough to make its extraction a profitable labor. Another discovery followed, that the dirt in immediate proximity with, and in which the quartz was imbedded, was rich, often richer than the quartz itself, and it was not until many tons had been thrown away or mixed up with valueless dirt that this fact became known, and now, on visiting a mine, you will see its pile of quartz on one side and its pay dirt, as it is termed, on the other. The first mill erected here was a small one, by water power, which proved a failure. This proceeded from the want of a proper application of the power. The next was a twelve-horsepower steam engine, which was abandoned or sold out by the company, after involving them in debt. Another steam mill of the same power was put into operation and by being properly constructed and prudently managed, was successful, and this company became the purchasers of the first steam mill, and after spending money enough to get it into the right condition and making such improvements in the mode of saving gold as were suggested by their experiments, this mill was made effective.
Other mills were then erected, having the benefit of the experience of the pioneers, and they have gradually improved one upon the other, until all are now able to save much more of the precious metal than it was possible to do in the first experiment--enabling them to crush poorer rock and at less prices than at first, and make a profit to themselves and to the miner.
Experience develops facts, too, which are of the utmost importance to those who would engage in gold working. The estimates of the capabilities of the machines for crushing have generally been too high--where it was confidently asserted that thirty and forty tons of rock could be crushed in a day, it is found that ten to fifteen is the result, by the power applied, and when the power of the engine has been called from twenty-five to thirty-five or forty horse, it may go from fifteen to twenty or twenty-five. Sufficient power is absolutely important, and too much is far preferable to too little. The expense of running an hundred-horsepower engine is but a trifle more than that of a ten-horse, being chiefly in the amount of fuel consumed, and when forty or fifty tons of rock is actually crushed in a day, the profit to the mill as well as to the miner is proportionably great. Poorer rock can be worked, and at a less price, and it is a mistaken idea to suppose that all veins are equally auriferous. Some will yield little or nothing, others will barely pay, while some are decidedly rich, and these varieties not unfrequently occur in the same hill, and there is a difference, too, in the same vein, but so far as my experience goes, the same vein will give a fair general average. While some veins will yield an average of five cents, others will give only three, two, or perhaps less, and a mill of forty horsepower can make money in working a medium average of rock, while a tenhorse would run in debt. Instead of there being a single general vein running through the country, with lateral veins, as I once supposed, we find several veins often in the same hill, some rich, some of medium value, others of little value. An experienced eye will detect the quality of the rock at a glance; that is, he can tell with much probability whether the vein will pay for working or not, and if there is doubt, he can determine by a simple process with much certainty, so that money and labor may be saved before large investments are made. And in prospecting too, a man accustomed to it will find the locality of a ledge by a process he can hardly explain, where others would pass it unnoticed. There are mills here which are working on three differnet principles. First--the stampers, by steam; second--a small water mill with six stampers on the triphammer principle, with a flutter wheel about thirty inches in diameter, in which there is a great waste of power as it is arranged; and the third is upon the Chilian system, having four uprightcrushing wheels, the individual weight of which can be made to reach twenty-five hundred pounds. This last is nearly ready to run. The two first do the work very well; as for the last, if I may be allowed to hazard an opinion, it will, I think, be found that it will crush the rock admirably, as well perhaps as is desired, but that it cannot crush as great an amount in a given time as the stampers. Still this remains to be seen. One apparent advantage that it suggests is that the amalgamation proceeds with the crushing, and hot water will be used, which will expand the quicksilver, giving it a greater surface and consequently collecting more gold than by the ordinary amalgamating process. Another water mill is in progress of erection about two miles below here by Mr. Kelly, having a water wheel of thirty feet in diameter, where there will be not only a great saving of power but thousands of dollars a year in the way of wood, engineers, firemen, wood-choppers, &c., &c. His mill will probably work as well as any in this vicinity.
Experiment has proved that only about one half of the gold is now saved by the improvements which have been made since the commencement of operations. A small quantity of rock which had been worked over was submitted to chemical analysis, when it yielded in addition at the rate of ninety dollars per ton, showing that an ample field for investigation and experiment is still open to the scientific and ingenious. You will frequently hear of rich specimens being found in quartz. This is so, but do not confound this with the average yield.--All paying veins will occasionally produce rich specimens, and although it is desirable to see gold visible to the naked eye in quartz, it is not necessary in order to determine whether it contains gold or not.
I do not know that any positive maximum of the amount which an engine can crush or not has been arrived at, but suppose it will be from half a ton to a ton to the single horsepower, carrying the necessary gearing and machinery. But one thing is certain, powerful engines are more profitable than small ones, and I think that in a short time the small engines in the country will be abandoned, to be superseded by more powerful ones. Lest I be thought too prolix, I will bring this subject to a close, only observing that what I write or have written has been according to the best information I could obtain at the time. Since my first communication on quartz mining, I have acquired more particular knowledge. It still continues to excite a lively interest in our State. Among other distinguished visitors to Grass Valley, General Atocha, of whom you are cognizant, has made a tour of observation, and it gave me pleasure to afford him all the knowledge I possessed of mines and mining. I found him an intelligent and agreeable gentleman, with enlarged views and a mind capable of formingand carrying out great designs, and I have spent no time more agreeably in California than the two evenings and one day that we were together. I sincerely hope that the result of his investigations may prove profitable both to himself and Mexico. Ex-Governor Blanshard, of Vancouver Island, and Captain Fanshawe, of the British Navy, were here at the same time, and all seemed delighted with their visit. It is a pleasure to meet gentlemen of any nation.
- Alonzo Delano