It is a subject of vital importance, not only to inventors but to the community at large, when it is proposed to discuss the workings of a system of laws relating to useful inventions or discoveries and their encouragement, and to propose or advo-' cate changes therein, and one that should call for a full and free expression of opinion in order that all interested may understand some, at least, of the probable consequences thereof. We have at present laws regulating the granting of patents, the principal feature of which is a full preliminary examination ; and it is supposed by legislators, and others, that such feature has been well tested, or at least ought to have been, by this time. The question then arises with respect to it. " Are we ready to pronounce it a failure 1" And if so, and in order to come to the conclusion that a radical change should be made, by doing away with such examination, are we prepared to assume that the same or increased benefits will flow from the change ? May not possibly evils spring up in other directions, for we must bear in mind that the whole system of protection is an artificial one, and its defects inherent from its nature, no matter how the system is established by a code of laws for practice. Assuming that the preliminary examination does not prevent tho granting of invalid patents, it is not shown that little or no precaution, as practiced at the present time in England, will do so wholly or to a very considerable extent, and it therefore reduces the question of change merely to one of saving the expense of our present system. Here, however, it will be well to consider if this course may not be poor economy, when compared to the. advantages gained by the adoption of at least some precautions against the granting of invalid patents. In carrying out the system, as adopted in England, in order that the trouble to be anticipated in another direction might not occur, namely, the rapid increase of invalid and annoying patents, it would be necessary, also, to introduce the payment of large fees by patentees. But this the patentee ought properly and will resist, as it tends to impede the developing and patenting of that class of improvement, and which is by far the largest, which progresses by small stages only, but each step of which must be necessarily protected as it is developed. Can we be satisfied that a system not requiring a preliminary system of examination, will work well in a community where invention is so rife, and patents have been found so lucrative as property, that many persons will patent not only their own actual improvements, but what they for a time 'merely believe to be theirs, without the payment of large fees, thereby tending to prevent an indiscriminate issue of patents? Even in England, however, with their enormous patent fees, the industries of the country do not solely receive benefit from, but are frequently burdened and oppressed by,the granting of patents. It is a question to be considered, then, whether the trouble in that country does not arise from the want of a proper system of preliminary examination, in order that the industries may be relieved, at least, from a large portion of the worthless and invalid patents that have been and will still continue to be granted. The English do not believe that the system of preliminary examination would relieve them much, because they do not think that any examining corps would be competent for the work assigned them, and they look at what the Americans have done in this wise to be to a great extent a failure. It is evident, however, from all accounts, that their open system of granting patents is not wholly satisfactory, and it is, perhaps, only their extravagant fees which prevents an expose of the worthlessness of their system, so far as the protection to the public and the community is concerned from worthless and frivolous patents. Even now the English manufacturer is compelled to buy up useless patents, that have been run through under their system, as a means of avoiding litigation, upon the principle that it is cheaper to buy off than to fight. To what the American manufacturer and capitalist would be subjected in this way under a similar system, with a moderate system of fees, there is no arriving at,except by an actual trial of it. As all inventors are to be protected, according to the policy for many years past in existence here, in their inventions, no matter how small the degree of novelty and utility is, it js apparent that in order to keep this species of protection within reach of all, the fees must not, if at all, be much increased. And if not increased will not the door be open to the granting of a species of patents that will be taken out only for fraudulent purposes, which will cause the grant issued to the really meritorious inventor to be at least looked upon with suspicion, and himself and those interested be placed at greater trouble and expense than at present to establish his patent before the public ? The English have complained of the practical inconvenience from the multiplicity of patents, which, under their system, have been issued only as obstructive patents, which means patents that are issued to harass and annoy manufacturers and tradesmen, and are to be got rid of economically only by being bought up. Are there not sufficient facilities for this thing now under our present practice without aggravating the evil ?—a system which at least does not let everything slip through. It maybe found, after reflection, that it is not our system that is at fault, but the way in which it is carried out, and, therefore, the reform ought perhaps be limited to merely making it more effective by correcting its abuses. The most perfect system may be rendered odious by the manner in whichit is practiced, and its abuse, in this particular, very often makes those most nearly interested unwisely denounce the system itself and seek for relief in a radical change, although such change may not always bring about the desired results. Extraction of Potash from “Yolk,” “Suint,” or Po tassic Sudorate of Sheep's Wool (From Dr. Hoffman's '' Report on Chemical Products and Processes," International Exhibition, 1862.) It is well known that sheep draw from the land on which they graze a considerable quantity of potash, which, after circulating in their blood, is excreted from the skin with the sweat; in combination with which it is deposited in the wool. Chevreul pointed out that this peculiar compound, by the French called suint, forms no less than a third of the weight of raw merino wool; from which it may be readily dissolved out by simple immersion in cold water. In coarser wools, it is less abundant; and according to MM. Maumene and Eoge-let, the potassic sudorate, or suint, of ordinary wools forms on the average, about fifteen per cent of the weight of the raw fleece. This compound was formerly regarded as soap ; doubtless because wool contains, beside the suint, a considerable proportion (about eight and a half per cent) of greasy matter (Chevreul). This grease however is, in fact, combined with earthy matter, chiefly lime, as an insoluble soap. The soluble sudorate is, according to MM. Maumene and Eogelet, a neutral salt, resulting from the combination of potash with a peculiar animal acid, of which little is known beyond the fact that it contains nitrogen. At the great seats of the woolen manufacture in France, as at Rheims, Elbeuf, and Fourmies, the new industry of MM. Maumene and Rogelet is either established, or in the course of establishment. Their plan is to buy of the woolen manufacturers the solutions of suint, obtained by the immersion of their raw fleeces in cold water; paying higher, of course, for those liquors in proportion as they are stronger. The scale of prices adopted encourages the manufacturers to wash their wool methodically, so as to enrich the same wa- J ter with the suint of a number of fleeces ; and these scour-ings, weak or strong, MM. Maumene and Rogelet fetch away in casks to their factory, established in the neighborhood, and then boil them down to a dry carbonaceous residuum. This, by calcination in. close retorts, is reduced to a charcoal, evolving during the process much gas, carbureted and ammonia-cal, which may be passed through ordinary purifiers, to detain the ammonia, and to fit the carbureted hydrogen for illuminating purposes. The alkaline salts remain in the charred residuum, and may be extracted therefrom by lixivia-tion with water. The alkaline solution thus obtained, contains a mixture of potassic salts, carbonate, sulphate, and chloride, which are separated and purified by evaporation and crystallization in the usual way. The carbonate of potassium thus obtained is stated to be remarkable for its entire freedom from sodic admixture, a purity doubtless valuable to the manufacturers of potassic glass and soap. The insoluble residuum of this lix-iviation contains some earthy matters (lime, silica, and alumina, with a little iron .and phosphoric acid), and it is stated to be so finely divided as to make a good black paint, possessing, in technical parlance, great " covering power." An ordinary fleece weighing four kilogrammes contains, accord ng to MM. Maumene and Rogelet, about "six hundred grammes uf sudorate of potassium or suint. This, according to their analysis, should contain thirty-three per cent of its weight, i.e., one hundred and ninety-eight grammes, of pure potash. Of this, according to another estimate (showing the niter that it would produce), they appear to reckon on about one hundred and seventy-three grammes as being practically recoverable. It appears from statistics given, that the process may be worked on a large scale, and with a very ample profit. MM. Maumene and Rogelet compute that if all the fleeces of French sheep were subjected to the new treatment, France would derive from her own soil all the potash she requires. The difficulty of collecting the wash-waters of fleeces, scoured in small numbers by the farmers all over the country, would oppose an insuperable bar to such an extension of the process. In great manufacturing centers it appears likely to be economically available; at any rate so long as the farmers continue to send away as waste matter, in the fleeces they sell, the potash drawn from the land. Doubtless, in honest husbandry, that potash is due to the source whence it came. Its exportation, year after year, must tend to the progressive exhaustion of the soil; and the policy of the judicious farmer should be to soak his fleeces at home, and to distribute on his fields, as liquid manure of high value, the potassic and nitrogenous wash-waters so obtained. The Self-raising Flour of Prof. Horsford, and Jones and Standing's Corn Flour Our readers will recollect Prof. Horsford's lecture on " The Philosophy of the Oven." Since that time we have been experimenting in various ways with the preparation therein described and with the most gratifying results. "We saw in a recent English periodical, in an article on celebrated cooks, a ! remark that cooks, like poets, were born not made. Our own gifts in that line have generally been supposed not to be great. In our youthful days we onco made an oyster stew in a tin paste dish cleaned out for the occasion in a rural printing office, which resulted in making " pi" of an entire form, which unluckily occupied the " stone" upon which we proposed to serve our repast. The stew did not taste well, whether on account of being eater after "pi" or our want of skill in its prep- aration, we cannot say, and we have remained in doubt up to the date of our recent experiments, as to whether any amount of " making" would compensate for our natural deficiencies. Our doubts are, however, ended. We are able to make anything of which flour is to any degree a constituent, and make it well too. Bread, white and light; crullers, tender and delicious ; apple dumplings of the most tempting character have been the result of our manipulations. The next trip we take to Brown's Tract, this article shall form a part of our stores. All that is necessary to make a good loaf of bread is some water, a pan, a spoon, Horsford's prepared flour, and appara tus for baking. The success of the process depends upon no variable circumstances but upon actual measure; it is therefore uniform. We have eaten of the bread for weeks, and either hot or cold it is both palatable and digestible. Another preparation which is worthy of commendation is Jones & Standing's corn flour. It is prepared by mixing In dian corn flour with " wheat bran dustings" and " middlings" by a process patented, together with the preparation after it is made, by Charles Jones and William Standing, of De Soto, 111., Jan. 5th, 1869, We have also tried this preparation and find that it makes most excellent bread, somethinglight-er and better than we have ever before tasted. Those who are fond of good corn bread, and those delicious corn cakes for which many parts of the country are celebrated, will confer a pleasure upon themselves by a trial of this corn flour, which is as wholesome as it is palatable. Manufacture of Paper from Okra We condense from the Mobile Weekly Register an account of some experiments which have been in progress during the last two or three weeks at the Chickasabogue Paper Mills, near Mobile, under the direct supervision of Dr. J. B. Reed, well known as the inventor of the Reed Shell which has rendered the Parrott gun so effective an engine of destruction in warfare. The inventive genius, energy, and perseverance of the Doctor were this time, however, directed to the " arts of peace." The above journal asserts that previous experiments had demonstrated the fact that good brown paper could be made of okra, but it remained to show that this material could be bleached to sufficient whiteness to make it available for printing or book papers, and if so, at what cost in comparison with rag or other material. On page 86, Vol. XIX, of the SCIENTIFIC AMERICAN we de scribed specimens of okra paper ranging from coarse brown to finest white, therefore the first of the above objects was already determined. The comparative cost was, perhaps, an unsettled question. The experiments were conducted under unfavorable circumstances. The material used was, for the most part, very inferior of its kind, and the orders for paper pressing on the mills, required that as little of the time of the employe's, and as small a portion of the machinery as possible, should be yielded for the purpose; consequently most of the work was done without at all disturbing the regular operations of the mills. The experiments were concluded on Friday last, and the result was eminently gratifying to those engaged in them, and is of particular interest to the press, dealers in and manufacturers of paper generally, and to farmers and gardeners in the South within reasonable distance of paper mills. In the opinion of the experienced paper makers who watched the progress of the work from the cutting of the dry stalks of okra to the production of paper from the machine, the following points may be regarded as established: 1. Okra requires but little handling to prepare for boiling, is readily passed through the cutter, needs no sorting, and the entire plant is available from the root to the pod. 2. It is easily boiled if well cured, requires only lime to reduce it, and may be washed and beaten ready for the machine in about half the time required for preparing rag stock, thus largely increasing the productive capacity of the mill without additional machinery. 3. When properly boiled it yields readily to the action of chemicals and can be bleached with no greater expense than ordinary rags. 4. The pulp works as freely and smoothly on the machine as any other fiber—does not stick to metallic press rolls like straw or wood, even when working pure okra pulp. It dries readily and can be run safely at the highest speed of the machine. 5. The paper made from it is very strong, tough and elastic—better in these respects, when made entirely of okra, than either straw or wood pulp when mixed with fifty per cent or more of rags. It has none of the brittleness and hardness so objectionable in straw papers, and may be subjected to strong friction by rubbing between the thumb and fingers, or between the hands, and will open out smoothly and soft as a glove. 6. It will make an excellent substitute to mix with other fibres in the beading engines, and is of itself a superior hard stock. 7. Whether worked pure or mixed with rags, it makes a paper entirely free from the objections justly raised by the printer against straw and wood papers. 8. It makes an excellent stock for fine wrapping paper, and imitation manilla paper, and even in its raw state withowt boiling or bleaching, makes a strong article of common wrapping paper, suitable for grocers and hardware use—superior to any paper made of straw. THE PKESIDENT has appointed Chauncey Snow, one of the proprietors of the National Intelligencer, as a Government Director of the Union Pacific Railroad, vice the Hon. James S. Rollins, of Maryland, resigned. Mr. Snow is a practical railroad man, having surveyed and located several of the western railroads, and having also been an engineer, for many years, of the Philadelphia, Wilmington, and Baltimore Railroad. Steam Gages and their Tests. The steam gages manufactured by the Utica Steam Gage Co., are so well known and appreciated that it is unnecessary to negatively set forth their excellences by any labored at tempt to decry the qualities of others. A description of the gage and its parts and of the method of testing its accuracy will be sufficient. Fig. 1 stows the face of the gage, and Fig. 2 the inside with the face removed. Fig. 3 represents the apparatus for testing the gages. A is a tube more than fifty feet in hight terminating at its base in a reservoir, B, of mercury. C is an ordinary galvanic battery, having one of its poles in the mercury in the tube and another in the hand, which is insulated, on the register, D; the wire connecting this hand with the battery passing around a temporary magnet in the register, which magnet works the bell hammer, E, striking the bell, F, whenever a circuit is made. At proper distances from each other in the tube, Aj are insulated points, Gr, piercing the tube and successively connecting with the mercury as it rises, each point being connected by a wire with a corresponding insulated point on the face of the register, D, these points being numbered to indicate the actual pressure of tho ntercury when standing at the correspondingly connected points of the tube. In short, the graduations of the tube are brought on to the face of the register, and are read from it. To use the apparatus, place the hand of the register, say on the second point on the face of the register, which is marked, 5 ; as it is connected with the second point of the tube, and the graduations are of five pounds each, and forcing the water into the gage to be testd, and at the same time upon the mercury in the reservoir, the hand of the gage begins to turn and the mercury to rise in the tube, until the instant the mercury reaches the second point in the tube, the circuit is completed, the bell sounds and the dial of the gage is marked at the spot indicated by its] hand, to show a pressure of five pounds. Moving now the hand of the register on to the third point on its face, marked 10, and proceeding as before, when the mercury reaches the third point in the tube, the bell again sounds, the mark to show ten pounds pressure is made on the dial of the gage, and so on until1 the gage is graduated. The accuracy of the instrument is proved by removing the gage, H, placing the hand of the register, D, on the point marked O, on its face, and using the pump until the water appears even with the top of the coupling for connecting the gage, H, when the bell should sound, the mercury then standing at the starting point in the tube, A, and allowance being made for the pressure of the water contained in the tube, 1, of the force pump, J, which takes water from the reservoir, K, and on the surface of the mercury in the reservoir, B. The spring of which Fig. 4 is a section in perspective, is made of two flanged corrugated disks, A, of spring brass, and a band, B, of brass, which is spun up without seam. In this band a groove is spun,* which forms a shoulder or seat, against which the disks rest, when pressed to their places in the band, one above, the other below the prooye. The edges of t]je band project beyond the flanges of the disks, are soldered and then spun or locked over the flanges, holding the disks firmly, without interfering with their elasticity. The lower disk has a pipe fixed. in its center by which it is fastened to the gage case and through which pressure is communicated to the interior of the spring. The spring is an inch and three-quarters in diameter and is capable of an expansion of 1-12 of an inch without injury. It is claimed that the objection made to ordinary disk springs, that after being used for a time they either become set or the disk cracks, is fully met in the construction of tliie spring. While the corrugations of the disks alone, would not be adequate to meet the strain which would fqllow the application of pressure, these are supplemented by the flanges, which give as occasion requires, and by the band, which is elastic. The strain instead of coming most severely upon the edge of the disks, as is the case where these are fastened in a rigid manner, and where the fracture generally occurs, is distributed equally throughout this spring. The movement by which the action of the spring is conveyed to tle dial is simple in its character ancl readily under- I stood from an inspection of the engraving, Fig. 2, in which it. 1! is represented. It is of cast brass, and is made and fitted from gages. It is fastened to the case by two substantial screws at the bottom of its frame, on each side of the spring, the rest of the frame being set away from the back of the case, leaving I the index hand wholly unaffected by any springing of the | case in putting the gage up, which sometimes, happens. By r bending the tongue, C, of the sector, Fig. 2, backwards or for-! ward, the leverage is altered and the gage can readily be ad-s justed to the correct standard, should it ever require it. The L index hand of the dial is left free from any action other than. that of the varying pressure witliin the spring, and the vi bration of tlie hand so common in gages upon locomotives, is wholly avoided. The gage is graduated from the patent mercury column, invented by the patentee of the gage and is thoroughly tested by steam pressure, in addition, before leaving the works. These gages have been before the public for five years and some 5,000 of them are now in actual use. Manufactured by the Utica Steam Gage Co., Utica, N. Y., to whom all orders and communications should be addressed. Cerium. Woehler has prepared metallic cerium in the following way : A solution of the oxide in hydrochloric acid is mixed with equal parts of chloride of potassium and chloride of ammonium and evaporated to dryness, fused, and poured out to partially cool, and then coarsely pulverized and mixed while still warm with pieces of sodium, and the whole projected into a clay crucible previously heated to redness. In this manner the cerium is reduced, and appears in the slag in the form of two pellets, which can be collected anJL fused into one mass. The color of cerium is between that of iron and lead, and when cut and polished exhibits a high metallic luster. It is easily hammered into a thin leaf, and can be cut like lead. Its specific gravity is 5*5, though this must be taken as only approximate, as the specimen tested was impure. The metal has no application in the arts, and is of very rare occurrence. Some of the salts of ceria are, however, highly prized in medicine. . gr The District of Columbia contains twenty-seven regular tel egraph offices, exclusive of fire-ralarm and police telegraph-stations. The bulk of these are, in Washington from whence they transmit news, at all houijs of the flay or nigat, to t press at all points of the. country.