Injury of Turpentine to Paint. Injury of Turpentine to Paint. By ROBт. R. HARDEN. [From the Southern Planter.] We use paint on our wooden buildings with two objects: first, ornament-second, durability. Was oil used by itself, without any coloring matter, the wood would be made more durable than it is with paint; but as ornament is a considerable part of the objects of painting, and as the addition of paint to the oil, when properly prepared, does not very materially injure the preservative quali. ties of the oil, the ornamental effect of the coloring more than counterbalances the injury it does. Paint, when properly prepared, therefore, while it is highly ornamental to wooden buildings, so materially contributes towards their durability, that there is economy in using it. But as it is generally prepared, (I may say always,) the ornamental effect of it on the outside of buildings is made only temporary, and its preservative qualities wholly destroyed. It is only necessary to look at our quickly decaying wooden buildings, with the paint washed off more or less in different places, according as it is exposed to the sun and rain, to be satisfied that the expense of painting has added very little towards preserving the building; and whether a building looks better without paint, or with paint nearly all washed off, with here and there a little remaining to show that it once was painted, taste must determine. If what I have stated be a fact, that paint, as mostly prepared, is of little value, it will be well to look into the cause of it, that the evil may be remedied; and if I give the correct cause, happily the evil is removed without expense or trouble; or rather, it is cheaper to paint well than in this defective manner. only to leave out the spirits of turpentine, We have and we will have good paint. Ask the painter why he adds it to the paint, and he will tell you to make it dry quick. This is just the same as saying, to destroy the oil, which renders the paint useless. Now let us reason upon it, and see if this is correct. If we pour oil on wood it soaks into it, and after it is all soaked up, if we apply more oil, it will strike still deeper and soak up more; when it has penetrated sufficiently deep into the wood as to prevent moisture from rain, &c.p penetrating as deep as itself, the wood is rendered very lasting. This would be the case if a building was simply covered with two coats of oil without paint. If we give it only one coat of oil, with a sufficient quantity of paint to give it color, the wood would so quickly soak up the oil that the paint would 305 be left a dry powder on the building, that give it first a coat of oil with a little paint would be easily rubbed or washed off. If we added to it, the oil soaks into the pores; another coat of oil with the proper quantity of paint, while the pores are filled with the recently put on or first coat, remains sufficiently long before the oil is soaked up by the pores for a part of it to dry with the paint, which forms a covering of paint. This is the advantage of giving two coats of paint; if the first coat was oil only, it would be better. injury done by the paint is the oil which it When a house is thus painted, all the retains and prevents from soaking into the wood; and this is in part, perhaps wholly, counterbalanced in forming a firm external covering, which tends to exclude moisture; thus painted, a building is preserved and ornamented. ing spirits of turpentine to the oil? We Now what will be the effect of add. know of nothing better calculated to destroy our intentions in the use both of the oil and paint than this addition of turpentine. Every housekeeper knows that if oil is on the floor, spirits of turpentine is the application to remove it. Every wash-woman knows that if oil is on her clothes, turpentine is the application to remove it; and how does it remove it when the oil and turpentine are added together? A chemical union takes place and the qualities of both are destroyed, and although either the oil or turpentine by themselves when applied on wood would add to its durabitity, yet when added together the original quality of both are destroyed, and the application is useless, just as an acid and alkali, when mixed together, destroy the qualiremains. Now, when a building is painted ties of each other and the effect of neither with two coats of paint to which spirits of turpentine is added, instead of the first covering of oil (which has very little paint) being soaked up, and the second covering, as the pores are already fed, soaking up the oil so slow that a part of the oil may dry in the paint, thus making a firm coat of paint on the surface, which will exclude moisture and prevent the evaporation of the oil, thus making the wood almost as lasting as time, and the color to remain as long as the wood lasts, what will be the effect of this addition of turpentine? The oil is decomposed, and instead of soaking into the wood and slowly drying in the paint to give a firm covering, it is quickly evaporated by the sun, the paint is left a useless powder on the wood; where it is not sheltered from the rain, it is soon washed away; and in places where it only gets wet without being washed off, as the qualities of the oil are destroyed, it retains moisture and hastens decay. We have only to go to a house which was painted white, and examine the somewhat sheltered spots where they get wet by showers, tho' the rain does not beat upon them so as to wash off the paint, and scratch off the paint, and we will find the surface in a state of decay, from the paint not excluding moisture, but retaining it. When pine wood is painted, it should more especially have only oil and paint without the spirits of turpentine, as there is in the wood turpentine sufficient to injure the oil. If we examine the shingles or weather-boarding of a house, we will find wherever there is a knot or fat place, there the oil is decomposed by the turpentine in the wood, and the paint destroyed, even where no spirits of turpentine was added to the paint. The oldest paintings we have appear as warm and glowing as when first executed, while the paintings of the first masters of modern times are injured, mostly as I think by the free use of turpentine. The fine paintings even of Sir Joshua Reynolds are losing their beauty. By some it is supposed that the paints used now are not as good as they were in former days. 'Tis not the fault of the materials, but the preparation. Oil, for instance, and white lead, are as good now as they ever were, and were they used without turpentine or any thing else, as the painters say to make them dry, (or as we say, to decompose the oil and destroy it,) would last as long and be as good as they ever were. If we calculate the annual amount of money used in the purchase of turpentine, and to this add the amount of loss from the injury it does, we will find it an enormous expense. Perhaps nine out of ten houses that take fire from sparks falling on the roof, do so from this mossy growth, which never is produced on wood that is oiled; were shingles dipped in hot oil before putting them up, it would be a preventive from fire from sparks. A few days ago, during almost a calm, at mid day, when only a few coals were in the fire place, my house roof was discovered to be on fire. As there was no ladder nor no way of get. ting at the fire, it seemed as though the house would burn down. A very strong man, how. ever, by getting in the window of a house not far off, was able to deaden the fire a little by throwing water with great strength; some drops would reach the fire: thus some little time was given for reflection. A man of great muscular strength with a small hatchet commenced cutting through the ceiling and sheeting. The fire began to blaze, the wind began to rise, all hope of extinguishing the fire was gone: he had however cut a hole through, and was able to tear off the boards and put out the fire. These shingles, upon examination, were found sound, but they were covered with this mossy growth. A very small spark must have set it on fire, for upon trial it was found almost as quick to take as gunpowder. Had these shingles been dipped in oil before they were put on the house, I would have been safe from such an accident, not only now, but for many years to come. Starvation Farm, Feb. 12, 1833. FOUL CASKS.-Foul pails, tubs, or casks, intended for butter or any other purpose, may be cleansed by putting in some bran, indian meal, or flour, and filling up with water; a fermentation will take place which will per. fectly cleanse the vessel. The liquid is the better for hogs after undergoing fermentation; consequently there is no expense attending the process. HANCOCK'S STEAM CARRIAGE.-The following letter of Mr. Hancock, showing the performances of his Steam Omnibus, is taken from Bell's Weekly Messenger, to the Editor of which it is addressed: Stratford, May 3, 1833. Sir,-More than six years have clapsed since I began my experiments on Steam Lo. comotion, and I have followed them with an ardor that did not admit of any diversion from the object which I kept steadily in view. During the past fortnight I have exhibited daily on the Paddington road a Steam Omnibus, the result of my experience; and hav. ing hitherto steered clear both of extravagant anticipations and exaggerated statements, I should be sorry now if any such should find their way into the public prints; and in order to prevent this, as far as I am able, I beg to hand you an account of each day's performance, if you think it is of sufficient interest to occupy a place in your columns. Having furnished these data, and given to the public opportunities of witnessing the performance of this carriage in the streets and on the most crowded and hilly road in the immediate neighborhood of the metropo. lis, I trust that I have demonstrated to the most sceptical the practicability of applying Public Instruction in France.-Of Wheel Work. steam economically to the purposes of inland April 22 From City-road to Padding- Miles. Total time. Delays. Travelling time. 307 one another. We shall now enter a little more fully into the subject and endeavor to explain some of the most useful principles upon which this branch of practical mechanics depends, and also to point out the various methods of applying this mechanical min. min. min. in the motion of different kinds of machinery. power Where a broad strap runs on a wheel, it is usually confined to its situation, not by causing the margin of the wheel to project, but, on the contrary, by making the middle prominent, as represented by the following wheel or pulley, on which a broad strap runs, the surface being convex; the wheel which drives it is of a similar form but its upper part only is shown in the figure. 23 City-road to Paddington, and back 8 71 25-From City-road to Paddington, and 26-Put in new piston, double the 27-Do. 29-Do. 30-Do. do. do. do. 9 62 64 11 53 9855 44 St 44 51 45 6 45 8 49 51 51 May 1-From City-road to Paddington, thence round Finsbury-square, and back to City-road 2-Do. 3-Do. do. do. 67 9 The average quantity of coke used has been three bushels each journey. I am, Sir, your obedient servant, W. HANCOCK. PUBLIC INSTRUCTION IN FRANCE.-The minister of public instruction in France has addressed circulars to the rectors, &c. for the establishment of schools for primary teachers. Within two years, this important class of schools,-in which we are so deficient in the United States,-has increased in number from 30 to 47. such school accomplish in each of our new What might one States. Much interest is shown in France, especially in certain departments, in the establishment of schools. The whole number of schools in the kingdom, in 1832, was 4,055, with 231,365 scholars: a greater number of scholars than in 1829. Schools have been established, where there were none in 1829, in 2,741 communes, (or townships.) The schools of mutual instruction have increased 536, and the normal schools 34. Schools and courses of instruction for the adults and laborers of Paris,-founded by individuals and societies,—are encouraged by the minister of public instruction, unless they have a political bearing.-New-York Advocate.] OF WHEEL WORK.-In treating of the simple mechanical power, called the wheel and axle, (see The Artisan, vol. i. p. 86), we stated that motion was communicated from one wheel to another, either by belts and straps passing over them, or by teeth cut in the circumference of each, and working in The reason of the middle being made pro. the manner in which a tight strap, running minent may be understood by examining on a cone, would tend to run towards its thickest part. Sometimes also pins are fixed in the wheels, and admitted into perforations in the straps; a mode only practicable where the motion is slow and steady. A smooth motion may also be obtained, with considerwheels into brushes of hair. More comable force, by forming the surfaces of the contiguous wheels are formed into teeth, im. monly, however, the circumferences of the pelling each other, as with the extremities of so many levers, either exactly or nearly in the common direction of the circumfe rences; and sometimes an endless screw is substituted for one of the wheels. consequence to determine the curvature In forming the teeth of wheels, it is of which will produce an equable communica. tion. For the equable communication of tion of motion with the least possible fric. motion, two methods have been recommend. ed; one, that the lower part of the face of each tooth should be a straight line in the direction of the radius, and the upper, a por. tion of an epicycloid; that is, of a curve the wheel, of which the diameter must be described by a point of a circle rolling on half that of the opposite wheel; and in this face of each tooth will act on the curved case it is demonstrable, that the plane sur. surface of the opposite tooth, so as to pro. duce an equable angular motion in both wheels: the other method is, to form all the It may be experimentally demonstrated, that an equable motion is produced by the action of these curves on each other; if we cut two boards into forms, terminated by them, divide the surfaces by lines into equal or proportional angular portions, and fix them on any two centres, we shall find that, as they revolve, whatever parts of the surfaces may be in contact, the corresponding lines will always meet each other. Both of these methods may be derived from the general principle, that the teeth of the one wheel must be of such a form, that their outline may be described by the revolution of a curve upon a given circle, while the outline of the teeth of the other wheel is described by the same curve revolving within the circle. It has been supposed by some of the best officers, that the epicycloidal tooth has also the advantage of completely avoiding friction; this is, however, by no means true, and it is even impractica. ble to invent any form for the teeth of a wheel which will enable them to act on other teeth without friction. In order to diminish it as much as possible, the teeth must be as small and as numerous as is consistent with strength and durability; for the effect of friction always increases with the dis tance of the point of contact from the line joining the centres of the wheels. In calculating the quantity of the friction, the velo. city with which the parts slide over each other has generally been taken for its measure; this is a slight inaccuracy of conception, for the actual resistance is not at all in creased by increasing the relative velocity; but the effect of that resistance, in retarding the motion of the wheels, may be shown, from the general laws of mechanics, to be proportional to the relative velocity thus ascertained. When it is possible to make one wheel act on teeth fixed in the concave surface of another, the friction may be thus diminished in the proportion of the difference of the diameters to their sum. HAMILTON'S PATENT SAWING AND BORING MACHINE. We have experienced much gratification in examining this useful laborsaving machine; and we are perfectly satisfied that it is destined to be of great public utility in cheapening the price of those articles which are in use by all classes of society, and will at the same time be a source of great profit to the ingenious mechanic who has invented it. We have no means of ascertaining the precise amount of labor and expense which this machine will save, but we venture to hazard the opinion that a man and two apprentices will accomplish more in twelve hours than forty experienced journeymen can accomplish at the same work during the same period of time. It is withal one of those inventions which require no extraneous aid to bring it into immediate usefulness. The proprietor has commenced working it daily, and in a ware-room adjoining the machine he offers for sale its produce at from thirty to fifty per cent. less than the market price. This simple fact and the certainty that the work is in all its parts more perfect than that manufactured by hand, has produced a demand more than equal to the supply. The machine is admirably well adapted to any sort of sawing that is usually done by hand or cross-cut sawing. Tenons, mitrejoints, &c. are cut with the greatest precision. In all sorts of pannel work and small framing it will be very useful. It is peculiarly adapted to sawing regular and eccentric circles, such as felloes for wheels, chair tops, seats, legs, and backs, and circular blocks for brushes; and it saws chair tops and seats with great accuracy on a bevel. Specification of a Patent for an Improvement in sawing Marble, &c. 309 Each segment of a wheel is cut its proper ance with it will enable any one, whether length and proper inclination for the joint- mechanic or otherwise, to operate on it as the holes are bored for the dowels and well as the inventor. It is only six feet spokes, and the hubs are bored on a prin- square, and is propelled by a steam engine ciple entirely new, making every spoke stand of two-horse power. with the greatest exactness from the centre to the extreme of the circle. The machine is perfectly simple in its construction, not liable to get out of repair, and easy to man. age and understand. A few hours' acquaint A part of the principle of the same ma. chine is applied to a small portable frame, and used for sawing wood for the fire with a rapidity really astonishing.-[Courier & Enquirer.] Specification of a patent for an improvement in the method of sawing Marble, and other stone, and cutting or working mouldings, or groovings, thereon, and polishing the same. Granted to Isaac D. Kirk, city of Phila. delphia. [From the Journal of the Franklin Institute.] References-A, The saws, or the mould. ing cylinder of soft cast iron; B, Carriage to support and carry forward the marble, or stone; C C, Rails on which the carriage travels; D, Hopper for sand and water; E, Apparatus for advancing the carriage. To all to whom these presents shall come, be it known, that I, Isaac D. Kirk, of the city of Philadelphia, and state of Pennsylvania, have invented a new and useful improve. ment in the method of sawing marble and other stone, and cutting, or working, mould. ings, or groovings, thereon, and polishing the same; the sawing being performed by means of an improved revolving, circular, metallic plate, smooth, or without teeth, upon the face, or edge, operating by friction with sand and water upon the material to be cut; and the moulding, or grooving, and polishing, being effected by means of the improved revolving moulding and polishing cylinder, or wheel, operating in cutting mouldings by friction with sand and water upon the surface to be wrought; and in polishing by friction, in like manner, with putty, buff, pumice-stone, or some other suitable material; viz. one or more circular metallic plates, smooth or not serrated upon the face, or cutting edge, (copper, or soft iron, are deemed preferable,) are securely fixed, vertically, upon a horizontal shaft, or spindle, of iron, of any required di mensions, passing through the centre of the plate, or plates, and supported at each end by a proper frame of wood, or of cast iron, upon which the shaft works. On one end of the shaft is a cog wheel to connect it to the moving power. Where two or more plates are used on the same shaft, they are secured at the proper distance from, and parallel to, each other, by circular metallic bands of a thickness adapted to the intended thickness of the slab, or slabs, to be cut; which bands are fitted upon and around the shaft between the plates, or saws. Under the shaft, at the distance |