the new-york exhibition illustrated.

could succeed in imbuing their fabrics with its rich blue color. But here a colos-sal difficulty immediately occurred. All their colors had been previously appliedto their fabrics in the form of solutions, or by precipitation from solution. But no°ne could succeed in discovering any means of dissolving ultramarine: and, infact, from the nature of the substance, the discovery of any solvent for it was tobe despaired of. Under these circumstances, there was apparently as little pros-pect of success in fixing ultramarine upon cloth in such a manner that it could notbe washed off, as of fixing in the same way powdered charcoal or any other per-fectly insoluble substance. The aid of the chemist, so often invoked, was againsolicited, and the use of albumen suggested. Albumen is a liquid substance, solublein Water, which, upon the application of heat, becomes solid, and perfectly inso-luble in water. The white of eggs consists principally of albumen, and the whiteOf eggs mixed with water was accordingly the substance used by the calicoPrinters and dyers. The ultramarine in fine powder was diffused through thissolution, the mixture then applied to the cloth, and the albumen afterwards co-agulated by the application of heat. Every particle of ultramarine which adheredto the cloth, is thus enveloped and bound fast to its fibres by a coating of insolublealbumen, which wholly prevents it from being washed off by water. Modifica-tions of this process have since been invented which cheapen it very much, andWhich are now used very extensively in England and Scotland. The albumen olmilk is now substituted for that of eggs, and the buttermilk of the dairies, whichWas once wasted or fed to animals, is now sold to the calico printers.

Ultramarine has one property which gives cause of complaint to the manufac-turers of ornamental paper and others. This is its incapability of being polished0r glazed, as they term it, its peculiar structure being such, that a reflecting sur-face cannot be produced upon it. This property may be accounted for, by sup-posing the granular particles to possess an uneven vitreous fracture, like thatPossessed by the natural mineral lapis lazuli, so that the more a surface coveredWith ultramarine is rubbed for the purpose of polishing it, the greater the number°f minute irregular faces produced, which reflect light in all directions, and con-sequently the duller and less reflective the surface becomes. At the same time, ituiust be remarked that the beauty of ultramarine for most of its uses is due in agreat measure to this very property of producing a dead surface like deadenedsilver. There is a variety of ultramarine called ultrwma/rine green, which seemsn °t to have been introduced into the market to nearly so great an extent as theultramarine blue. There are on exhibition in the Palace several specimens of thisProduct, which present, nevertheless, a very good color, and when we considerthe economy which must eventually be found in the manufacture of this substancea bove all the other green colors at present in use, such as Paris green or Scheele sgreen, the main constituents of which are two costly substances, arsenic and cop-per, verdigris, which is also a copper compound, and chrome green, we mayreasonably expect ultramarine green to become in future an extensive article ofcommerce.

The various processes which have been proposed for making ultramarine green,ar e essentially the same as those for the ultramarine blue, except that the lastroasting, to drive off the excess of sulphur, is dispensed with, so that the soledifference between the two colors appears to be, that the green ultramarine con-fains more sulphur than the blue. Certain precautions are of course necessary toproduce a fine color, which are of interest only to technologists.

The ingredient or ingredients, in the natural and artificial ultramarines, towhich the color is to be attributed, is a question which has occupied the attention°f several chemists and given rise to considerable discussion, without, however, adefinite settlement up to the present time. At first it was attributed to thePresence of sulphuret of iron formed by the action of the sulphur upon small quan-tities of iron present in the mass and derived from the materials employed. Thishypothesis derived support from the fact that sulphuret of iron may be obtained,hy chemical precipitation, diffused through a liquid in excessively small quantity,in such a manner as to impart to the liquid a deep green, or even bluish-greencolor by transmitted light. This is a phenomenon frequently encountered bychemical analysis. Brunner and others, however, have stated that they haveprepared blue ultramarine from materials entirely free from the smallest trace of’ton, and if Brunner’s authority is received, the coloring matter of ultramarinemust he considered a substance sui generis, having no analogue whatever among allknown chemical compounds, being in fact a compound of sulphur, silicon, alu-minum, sodium and oxygen possessed of a blue color, whereas no two more ofthese five elements are known to form any other compound possessed of thesmallest tinge of blue or green color.

On a thorough consideration of the subject, however, the last hypothesis seemsh a rdly credible, and it appears probable that those chemists who have preparedultramarine from materials free from iron, have accidentally introduced traces ofthis metal during the process. Thus it is almost impossible for a chemist whoknows the affinity of sulphur for iron to suppose that they can coexist in the mass,together with soda, during the process, without the formation of some highlycolored compound, and the belief that ultramarine can exist, which is free fromir °n, involves the necessity of supposing that the highly colored sulphuret of irones isting in ultramarine which does contain iron, has little or no effect upon the

color. It is certain that some who have tried to obtain a blue-colored_ mass frommaterials containing no traces of iron have failed; but such negative resultsare, of course, of comparatively small value, and on the other side of the questionmay be brought forward the well known fact that the presence of more than anexceedingly small per centage of iron injures or ruins the color, and also the sin-gular fact, that if potash is substituted for soda, no blue or green color can beproduced under any circumstances, the corresponding potash compound beingwhite. This last fact distinctly connects the color with the sodium which ispresent, while the effect of dilute acids in destroying the color with simultaneousexpulsion of a portion of the sulphur in the form of sulphuretted hydrogen, indi-cates a probable, though not a necessary dependence of the color upon the sulphurThe whole subject, in fact, needs reinvestigation, and may be urged as beingdecidedly one of the most interesting subjects with which a chemist could occupyhimself, and one which promises important practical results.

In conclusion, a few applications of artificial ultramarine may be pointed outwhich may be seen exemplified in the Exhibition. Thus great quantities of sta-tionery in the American department may be seen, which are undoubtedly coloredwith ultramarine. Ornamental paper for walls and other purposes, among thecolors of which ultramarine forms a prominent ingredient, may be seen in variousplaces. Soaps and leather, colored with ultramarine, are on exhibition. Signsand placards composed of gilt letters, upon an ultramarine ground, are very com-mon. The backs of many of the show-cases are colored with ultramarine, itsazure color appearing to be a favorite tint for such backgrounds; and, lastly, itis an important auxiliary in the decoratiou of the Crystal Palace itself, a light-colored ultramarine having been largely employed in painting the roof and columns,as well as the canvas which covers the interior of the dome.

NAVAL ARCHITECTURE.

I T would he foreign to the objects aimed at in the Record, to attempt more thana mere popular elucidation of the principles of the science of naval architec-ture, in which the results of the last few years have established the United Statesin an eminent position. In the infancy of the republic, a happy preservation ofneutrality in the European wars, placed her, in connection with England, then themost powerful maritime nation, in possession of the carrying trade of the world.The English merchantmen were compelled to sail in company, under the protec-tion of a convoy, and the movements of the entire squadron being regulated bythose of the dullest sailer, superior qualities of speed were of no benefit, and theskill of her builders was centred upon attaining the greatest possible capacity fromthe measured dimensions. Her absurd tonnage laws afterwards sustained the eviluntil the system was too deeply rooted to be readily cast aside; and even at thisday, so superior are American ships, that British merchants prefer them as invest-ments, and own a large portion of the stock of the American transatlanticliners and packet ships.

The mathematical solutions of the various problems involved in ship building,are so largely modified by practice, that there is no necessity for following themfarther than to enable us to establish with certainty the effects of the differentproportions, and by experimenting understandingly, avoid a repetition of error,and expand to their fullest extent those principles which may prove advanta-geous. A convincing demonstration of the solid of least resistance is of little bene-fit ; but while records of mere facts of much less complexity than those involved inthis science have proved a facility for error in observation and omission, it be-comes necessary to reject all that conflicts with the known laws of natural philo-sophy, and cautiously receive whatever may not be in accordance with reason.Pure theory is perfect; but, unfortunately, too often becomes so only when thescience to which it is applied has been perfected.

With the other dimensions and conditions remaining constant, the immediateeffect of length is to decrease the direct resistance of the water to the passage ofthe hull, and to diminish the leeway and violence of the rolling and pitchingmotions. As, in the passage of the vessel, a distance corresponding to its length,the water is divided and separated a distance equal to the breadth of the section,it follows that a vessel, 200 feet long, will transmit no more motion in passing200 feet, than one of half the length will in going half the distance; the longervessel would displace double the quantity of water, but would communicate to eachparticle only half the velocity which it would have received from the smaller one;and as fluid resistance varies as the squares of the velocities, the resistance to ships,other things being equal, varies in an inverse ratio with the squares of their lengths.The length being doubled, theoretically considering this element alone, it wouldrequire but one quarter of the power. The benefit derived from the superiorityof acute angles for cleavage, is practically limited by the friction of the immersedsurface and insufficient buoyancy of the ends. The retardation occasioned by thefriction of the water has been too generally disregarded, and its importance isonly realized by making a calculation on a sea-steamer, where the power is known

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