J. P. S., of Obio.—Kerosene oil i3 more volatile tlian whale oil, hancs, if used in open lamps, it must be more injurious to health, but as it in burned in close lamps, it is just as healthy. W. J., of Tenn.—We cannot refer yon to any printed irork containing more information relating to the crystallizing of the sorgho sugar than is to be found in our columns. The business is new, and further experiments are required. M. and L. S., of C. E.—You willfindthat if you stamp out the copper bottoms of your tea-kettles with two or three blows, instead of by one heavy fall of the hammer, they will not be so liable to wrinkle. S. S., of Ohio.—Resin, wax and gutta percha will answer for insulating telegraph wires, but not quite BO well as glass. The larger the body of glas3 employed, the more perfect will be the insulation. C. J. W., of 111.—According to the law of diffusion, as It relates to gases, there is no greater affinity shown by one more than another in the dry state. Oxygen and hydrogen have an equal affinity for carbonic acid gas. Lime water is the best absorbent of carbonic acid gaa; fresh charcoal the next. J. G. B., of N. J.—Oufc naili are made from small plates of iron which are heated in fires near the machines to the proper temperature. I. P., of Wis.—Your sample of Indian hemp is not ao strong in fibre a3 American cr Manila hemp. We like the common plain board fence better than the one represented ia the sketch you have sent us. If the feet of the posts were bailed in a solution of sulphate of coppor or in tar, they would last twice as long in the ground. It is not the first but ultimate cost of fences to which farmers should look. Your plan is cheaper, but not so strong as the common fence. W. Fiahbash, of Stanarlaville, Va., wishes to correspond with manufacturers of bent brims for truck wagons. J. J. S., of 111.—We cannot supply Patent Reports to our subscribers. They must depend upon their mem-bsrs of Congress, aa the Commissioner of Patents has comparativelyfew copies at his disposal. L. M. M., of N. Y.—We do not know of the existence of any patent on an e&ve trough sawed out of plank. G. M. N., of Ga—We doubt whether any patent could be obtained on your rule. The slide rule, cither the carpenter's or engineer's, does the same thing and on the same principle. F. P. C, of S. C, wishes us to inform one of our correspondents in reference to his appliance for arresting bed-bugs in their progress up bad-posts, which we noticed in this column some weeks since, "that he need not trouble himself further, unless he can keep the aforesaid animals from crawling altogether, for I have known them to navigate up the wall, thence on the ceiling till well over their victims, then an easy let go, and all right for the night." W. R., of Ind.—From so small a specimen we cannot precisely tell what the mineral you sent us is, but we think it is carbonate of lime. If so, it i3 not what would be called poisonous, but if taken in large quantities would make a person very ill. We cannot divine why you ask such a question. You don't think of eating stones, do you? M. A., of Md.—It is impossible for us to give you the information wanted. We cannot tell you which 1B the tost waterwhsel, because tha efficiency of any wheel, independent of the principles of its action, depends on the workmanship. Contract with a millwright or wheelmakerto build a desirable one that will give out 75 per cent of the water power, and you cannot go wrong. G. P. T., of Me.—The creosote which forms in the pipes of stoves or furnaces in which wood is employed f orfuel cannot be prevented if these pipes pass through a cold atmosphere. The creosote is the acid of the wood condensed from the smoke. If you keep your pipes at the temperature of boiling water, you will not be troubled with creosote ; if you cannot do this, give them considerable inclination, so as to allow the acid to flow down and not lodge. J. R., of Ohio—Those wise men in your place who are determined to obtain thepovrer of twelve men from the labor of two, by swinging a long 1 ever, should be allowed to take their own couraa. After they have accomplished this grand object, they will be perfectly able to stop the flow of the Ohio river with a pitchfork. S. E. P., of Pa.—Any new and useful information which you can impart relating to saws, and the management of sawmills, will be very acceptable. H. H., of 111.—Wax is bleached by first melting it over water, with about one-fourth per cent of tartar, and constantly stirred ; it is then drawn off and allowed to run into cold water, and this ribboned wax is afterwards bleached by the aua Sunflower oil is made in precisely the same manner as linseed; in fact, all oils which are expressed from seed are made by the same processes As to whetherit would be profitable or not, we canno tell. Experience can only decide that question. P. C, of Vt—Kline's compass, with the iron ring surrounding the needle card, has been found more re liable on the steamship Adriatic than any of the common compasses on board. Something has been done towards nventing a pencil to write and make marks equal to pen and ink writing, but there is plenty of room lor you to operate ; pen and ink writingstill maintains its place for want of "the" perfect indelible writing pencil. Your bench hook, composed of a spring movable in a slot, and capable of being elevated and depressed by a screw, appears to resemble the old fashioned bench hook so nearly, that we decline giving you any encouragement as to its patentability. t P. E., of Ala.—We are very glad to hear of your ex ' cellent success with the circular sawmill. We hope the J promised models will be sent on'soon. B. L. G., of Pa.—It is customary with the Commis-ioner of Patents to send patentees a copy of his an-tual Report, which contains notices of their improve-uent3. D. B. B., of Pa.—We remember that your ca3e was hree times rejected before we finally succeeded with H. Ve eaw, upon a close examination into itu merits hat f ulljustice had not been done to it. We thank you or your good opinion of our exertions in your behalf. M. B., of Ind.—The earth completes its revolution ound the sun, as measured from any one period of time luring the year. It no more completes its revolution n the 22d of December annually, as asserted by the )hilosopher in your neighborhood, than on the 22d of September. J. H. K, of Mass., remarks, that we appear to have L mind of our own in spelling words. " You spell," he tays, "the word height hight, sol presume you would ilso spell chalk, chorh, and so I might go on, but time vill not permit." Our learned correspondent presumes i little too much, and no doubt his want of time has laved his own orthography from a violent wrench. We lo not profess to have a way of our own. We adopt the simplest method recognized by standard authority, and f J. II. K. had looked at Webster, he would not have betrayed his ignorance upon this subject. It is very 3vident that he has a different authority wholly unknown to us, as we perceive in his letter before us that ic spells the word "similar," simalar. It may be, how-aver, that some critics spell it in that way. G. S., of Pa.—There is nothing new in your boiler feeder. Such feeders, that is to say, consisting of a vessel arranged above the water level of the boiler, and connected with the steam and water spaces thereof, so as to enable the water in the said vessel to be placed in equilibrio, that it may descend into the boiler by gravitation, have undergone many modifications. The only one we are enabled to refer to particularly at the present moment was patented June 14,1854, by II. C. Sergeant, which ia entirely automatic in its operation. A. E. S., of Ind.—Gold pens are pointed with a metal called rhodium, and the tips are soldered on. Looking-glass frames can be prepared in the way you name, but they never are, beingalways gilded withleaf gold. Your method, of plating watch cases may produce a good gold surface to look at, but it will not wear. We would advise you to use the usual alloy for plating. The metal you sent us was iron pyrites or sulphide of iron, and is worthless. Gold foil can be beaten into watch cases or amalgamated on to them, but we are not aware that any cementing process is carried out by platers. G. & F. Spicker, of Cincinnati, Ohio, wish to corre spond with some manufacturer of round looms for making jackets. H. N. H. B., andM. V., of Cal.—We thank you for your generous lists of subscribers. You have done nobly for us, and we are very grateful for it Money received at the Scientific American Office on account of Patent Office business, for the week ending Saturday, January 16,1858 :— V. & H., of N. Y., $30 ; W. II., of N. Y., $25; P. C. M., of III., $25; W. CK S., of Mass., $55; F.. H. S., of Conn., $30; II. D. B., of N. Y., $25; E. S., of Conn., $30; L. D., of N. Y.,$30; R. H. K, ofN. Y., $25; H. & S., of 111., $25 ; P. A. G., Qf Mass., $30; W. & S., of Mass., $25; J. B. A., of L. I., $30; G. J. LM of N. Y, $57; L. W., of Ohio, $25; M. G., of Pa., $30 ; J. D., ot N. Y., $55; II. A. L., of N. Y., $30 ; C, L. C, of N. Y., $40; G. B., of Md., $30; T. D. I., of Mich. $55 ; L. R., of Mass., $40; D. K., of N. C, $55 ; A. D. B., of Mass., $110 ; F. N., of L. I., $10 W. H., of L. I., $25; S. L., of L. I., $30. Specifications and drawings belonging to parties with the following initials have been forwarded to the Patent Office during the week ending Saturday, January 16,1858 :— A. D. B., of Mass., (2 cases); D.R.,ofN.C; F. N., of L. I. ; L. B. S., of Conn. ; J. K. B., of N. Y. ; C. & Q., of Mass.; W. H., of L. I. ; P. W. W., of Texas; P. C. M., of LI. ; C. A. C, of Pa.; L. W., of Ohio ; H. D. BM of N. Y.; H. P., of Pa.; S. L., of L. I.; II. & S., of 111.; R- H. K, of N. Y.
This article was originally published with the title "Correspondents" in Scientific American 13, 20, 159 (January 1858)