J C R, of VaA patent cannot be obtained for any improvement but in the name of the inventor The apparatus for extracting tannin from bark, described by you, is not new, and therefore not pateutable Vegetable oils are generally injurious to leather, and so are some animal oils Flax, olive, and whale oils soon rot leather Tallow and neatsf oot oil make a good leather composition Tooth powders should be avoided, il possible; they are not required if the teeth are, as they should be, kept clean E B S, of IowaYou will find the artificial ears to ?which you refer, illustrated on page 67, Vol XII, Sci AM C O R, of N JThe fine gloss on shirtbosomscan be produced by a mixture of gum arabicvith the starch; but we believe that our city laundresses do it by the quickness with which they iron M F C, of IowaThe friction of your watertight joints through which D passes, would alone prevent your ever obtaining perpetual motion Turn your attention to something useful, and do not try to catch shadows M A W, of HIYou can precipitate iron from its solutions as sesquioxyd,by adding a solution of carbonate of soda It cannot be precipitated in a metallic state F L W, of S CWe could not get up nice engravings of your invention without the aid of a model to take the views from Engravings taken from the drawings which are attached to the Letters Patent can seldom be made to illustrate an invention in so practical a manner as when the views are taken from the machine or a working model; therefore it is as important to you to furnish good material, to get up your engravings from, as it is to ua E C M, of N YYour communications cannot be published We can fill our columns with matter of more interest to our readers than what you have "written P A P, of FlaA revolving battery intended for the use of war vessels, is not new If you have anything new in this department it can be patented Send us a sketch and description of it for examination A IT, of WiaThe employment of a long tube through which to run out the submarine telegraph cable, haa been already suggested to us J J, of OhioThe "Railway Association" for the encouragement of inventions, to which you refer, is non est invmtus The squaring of the circle means the multiplying of any part of a circle into such a number as will give the exact circumferencewithout a remainder R F, B, of MoYour plan of propelling boats by two directacting blades working in tight boxes through the stern of a vessel, is not new, except in being placed en an incline, and being lifted out of the water at each stroke This is not an advantageous method of operating ; they should be placed horizontally S R Reed, of Buffalo, N Y, wishes to correspond with the manufacturer of the ditching machine exhibited at the Elmira (N Y) Horse Fair last fall Inventors and patentees ?who hide their light under a bushel must expect to be neglected, or if found at all it must be by some such method ol pursuit as is adopted in this case Such requests as Mr Reed makes are becoming very numerous H H F, of MissWe are of opinion that your present patent covers tire modification of your machine, aa represented in the diagram you have sent us B B, of Ohio"Gloves made of stout cotton canvas, boiled in a strong solution of alum, and then dried thoroughly, should last much longer than either leather or india rubber, for handling potash Several methods for steering vessels have been patented; see Captain Brown's, illustrated on page 268, Vol 0, Sci AM L S, of IndYour idea of conveying gas in suitable vessels from place to place, for the purpose of illuminating small villages, is very old Many years ago a company was formed in London to manufacture illuminating gas, and deliver it to the consumers in bags at their own houses It was a failure J W H, of IndYour theory "that there are two funnelshaped holes running into the earthfrom the poles, through which light and heat enter into it, to disseminate their lifegiving properties, and which for forty years you have been maturing," is highly improbable Mariners and explorers have been very close to both poles, and have not seen anything of the holes; again, the penetrative powers of light and heat have been measured, and we know exactly how they penetrate the earth The facts are against you, and true theories can only be formed on known facts The idea is an old one, having been first promulgated by a Prussian philosopher in the time of Frederick the Great L K, of PaThe expansion of hot air is uniform The pressure increases one pound for every 33 degrees of heat The pressure is 15 pounds on the square inch, when raised to 490 degrees of temperature R B N, of PaYour barn being 40X90 feet, should be protected with a lightning rod at each end, which, should extend at least ten feet above the summit of the roof, and down several feet into the damp ground, or into a well of water Unite the sections perfectly together, and fasten the rod to the barn with glass cleets, or brackets of dry wood covered with shellac varnish The higher and thicker the rod, the more perfect will it be as a lightning conductor W J S, of Messrs Crum Paul have a patent for an improved process for making bread, but we are not aware of any patented machinery of theirs for this purpose If you had informed us in what State you reside you would have had our answer by mail ' several days since There are Newports in almost ' every State in the Union J R S, of VaWe advise you not to expand time and labor in experimenting with hot air engines No power can be obtained from contracting the airit is a mechanical impossibility The best way to use hot air is upon the principle of the noncondensing highpressure steam engine R D, of MichTin being dearer than copper, of course an alloy of these two metals is more expensive than brass made of zinc and copper Muntz metal for sheathing is composed of 70 per cent of zinc, and 30 of copper Bronze sheathing may be made with 95 per cent of copper, and 5 of zinc We have never seen copper coated on one side with tin as thick as the copper sheet The address of the Waterbury Brass Agency ia No 52 Beekman st, this city E E, of N YIf the circumstances are as you state them, Mr A cannot secure a patent on his alleged improvement ; but if his invention is new, no influence can possibly avail to prevent the issue of a patent to him Every case presented to the Patent Office is judged on its merits, and to attempt to stop a case by "protest," under the circumstances, would be ol no avail You can have an interference declared by making an application for the same device, and if you can sustain your right to it by proof of priority of invention, you can secure the patentnot otherwise T M P, of N Y To stamp an unpatented article ** patent right secured,11 would be a clear violation of the law and punishable by fine D A B, of AlaIf your plan for forcing letters through tubes, by means of atmospheric pressure was new, we should have no confidence that it would ever succeed Similar plans have been tried without success J B C, of IndIf you own the right in a patented invention for a certain territory, you can make and sell to any and all purchasers upon your own ground If parties purchasing are willing to run their own risk in attempting to use them upon the territory belonging to another, the responsibility tails upon them, and not upon you F J M, of MassWhen salt water is employed for steam bailers the salt sinks to the bottombecomes concentratedit does not rise to the surface ; and is removed either by a brine pump or blowingoff At the Mount Hope Iron Works, where the water is brackish, it must contain the carbonates and sulphates of lime, and will, therefore, readily form incrustations It ought to be purified before being admitted to the boiler; if this is not done, you must blowoff regularly at both the lower and upper blowoff cocks T B J, of MassWe are much obliged to you for your attention in sending us the extracts regarding the Russian steamer Manjoor M M K, of TexasYou say that owing to the long drouths of the summer and the ravages of the cuttin i ants, no hedging has yet been tried in your State that answered the purpose, and that by a careful study of the thorn shrubs of your region, you have found one that will stand these unfavorable conditions, and inquire if you can get a patent for it Surely not The patent laws have no provisions for the protection of such discoveries Your State ought to reward you if it proves permanently valuable H J H, of 111The philosophy of color is simple Colors are not substantives, but appearances caused by reflected light, and are no more material than the light itself When we see a color we know it is produced by a reflected ray of light, just as a shadow is caused by intercepted light; but neither the color nor the shadow are substances J (J, of TexasSilver or copper are the best metals you can use for electroplating You should get "Smee's ElectroMetallurgyj" published by Wiley Halstead, this city It will give you all the necessary instructions, and you may be able to construct your own batteries S W B, of VtThere are arrangements of gearing on various machines for communicating a fast or slow motion to machinerj' A cone pulley is the most convenient and common, but not the absolute method W H, ofYour gunpowder engine is new to us We cannot tell you what would be the cost of it as a power The sketch which you have sent us representing an endless belt of buckets is not a new water motor, but one that is as old as the genuine water wheel D A M, of PaThe number of the Set AM you wanted has been sent A millstone of Z% feet in diameter will not produce backlash so readily as one of four feet, if the revolutions of the two are equal, no matter what kind of gearing may be employed J D, of N YBlocks of granite about twelve inches deep, and seven or eight inches wide, set edgewise, are now employed for paving in thi3 city, and have been so used for a hundred years in Europe There is no necessity for using cement between the interstices, as these assist to give footing to the horses It makes a very excellent pavement, and your views in this respect are perfectly correct P V S of TexasWe are obliged to reject your article upon " weight and motion; " it is evidently not intended for our readers Your views are vague and incorrect C C, Jr, of MassThe " first" is the only edition we have seen of Minifie's work on drawing We do not know the price of pure metal cobalt, but the oxyd is sold at the rate of $1 per ounce W H L, of WisWe are quite certain that your hopes for a patent are futile, and we must discourage you When we say that we have had the same thing in our office, we mean it If you wish to try for a patent you can always depend upon our doing the best we can for you D A S, of WisEarthenware cases are among the earliest devices used for burial purposes We published a number of articles in Vol 5, Sci AM, proving the popular notion " that bodies will not sink to the bottom of the ocean at great depths," to be a popular delusion Money received at the Scientific American Office on account of Patent Office business, for the week ending Saturday, April 3,1858 : W H C, of 111, $27; J O, ofN Y, $305; S A, , of Mich, $25; J C, of N Y, $30; JJ C H,ofN 5 Y, $30; C M L, of Ohio, $25; G W S, of Ind, $30] r 0 S, ofN Y, $30 ; E G E, of K Y, $40; I Z A W, of Pa, $25 i L E, of Mich, $84 ; T H W Bros, of Ga, $30 ; L , of N J, $30 ; W W L, of Conn, $30; S T, of,$20; J W P, of Pa, $30; W D of Mass, $25 : W D J, of N Y, $25 ; F B ofN Y, $20 ; F J, of Ohio, $25 ; S H, Jr, of Vt, $10; N H S, of 111, $25; N A, ofN Y, $25; S W, of N J, $25; D B W, ofN Y, $30; L T, ofN Y, $20; H A N, of Mass, $30 ; W B, of N'J, $30 ; J C D, of Ky, $30 ; J C, of N Y, $30 ; B A E, of Conn, $30; J F K, of Ind, $25; G S E, of Ohio, $25; W C, ofN Y, $25; I E L, of Pa $55 ; C B, ofN Y, $35; W O P, of N Y, $25; J, T, of N Y, $25 ; T O, of Miss, $25 Specifications and dra wings belonging to parties with the following initials have been forwarded to the Patent Office during the week ending Saturday, April 3,1858 : J C S, of Mass; I Z A W, of Pa; W C, of N Y ; C F, of N 3; S A, of Mich; J W H, of E 1 ; C M L, of Ohio; W H C, of III; J E L, of Pa; J T B E, of N Y ; C B, OfN Y ; F J, of Ohio; W D, of Mass; W D J, of N Y; F B, ot N Y; W O P, of N Y ; N H S, of HI; N A, ofN Y ; S W,of N J; M GF, OfN Y; J F K, of Ind ; G S E, of Ohio ; J T, ofN Y ; T O, of Miss ; E G E,of N Y