COOLING OF FLUIDS.

317

whereby a new compound is formed; the heat and light evolved being most probablyproduced by the rapid motions of the particles during the progress of this combination.

COMPOUND COLORS. If the effects of the coloring particles did not varyaccording to the combinations which they form, and the actions exercised upon them bythe different substances present in a dyeing bath, we might determine with precisionthe shade which ought to result from the mixture of any two colors, or of the ingredientsaffording these colors separately. Though the chemical action of the mordants, and ofthe liquor in the dye-bath often changes the results, yet theory may always predict themwithin a certain degree. It is not the color appropriate to the dye-stuffs which is to beconsidered as the constituent part of compound colors, but that which they must assumewrth a certain mordant and dye-bath. Our attention ought therefore to be directedPrincipally to the operation of the chemical agents employed.

L.The mixture of blue and yellow dyes produces green. D’Ambourney, indeed,fays that he has extracted a fast green from the fermented juice of the berries of thebuckthorn (rkamnus fragula), but no dyer would trust to such a color.

2- The mixture of red and blue produces violet, purple, columbine (dove-color^,Pansy, amaranth, lilach, mallow, and a great many other shades, determined by the natureand tone of the red and blue dye-stuffs, as well as their relative proportions in the

3. The mixture of red and yellow produces orange, mordore, cinnamon, coquelicot,brick, capuchin ; with the addition of blue, olives of various shades; and with duns in-stead of yellows, chestnut, snuff, musk, and other tints.

. Blacks of the lighter kinds constitute grays; and, mixed with other colors, pro-. ”ce marrone (marroons), coffees, damascenes. For further details upon this sub-pbntj see Calico Peinting, Dyeing , as also the individual colors in their alphabetical

Concrete. The name given by architects to a compact mass of pebbles, sand,a lime cemented together, in order to form the foundations of buildings. Semplew y . s that the best proportions are 80 parts of pebbles, each about 7 or 8 ounces inWat t, ^ parts sharp river sand, and 10 of good lime; the last is to be mixed withas « e v. to a 'Finnish consistence, and grouted in. It has been found that Thames ballast,the 3 r n l ^ e r ' ver > consists nearly of 2 parts of pebbles to 1 of sand, and

cishtv,° re answ ers exceedingly well for making concrete; with from one seventh to oneis t' 1art I* me- Tbe best mode of making concrete, according to Mr. Godwin,>s n° BUX bme, previously ground, with the ballast in a dry state; sufficient waterl ea§ bw thrown over it to effect a perfect mixture, after which it should be turned over at•bsia n V ^ Ce with shovels, or oftener; then put into barrows, and wheeled away for usebperat ’ ’ * s S eneral ty fonnd advisable to employ two sets of men to perform thistu rn 10n > with three in each set; one man to fetch the water, &c., while the other twocon C re( er mixture to tbe second set, and they, repeating the process, turn over theWheel t0 barrow-men. After being put into the barrows, it should at once befouad^,. U P planks, so raised as to give it a fall of some yards, and thrown into theis givenT 1 ’ ^ which means the particles are driven closer together, and greater solidityto (, e . to the whole mass. Soon after being thrown in, the mixture is observed usuallyThe bar* 1 comrn °ti°n, and much heat is evolved with a copious emission of vapor,a stratnm°"r^° a ^ concrete in the fall, spreading over the ground, will form generallya second °* ^ rom ^ t0 9 inches thick, which should be allowed to set before throwing in

Anoth er

guantity 0 j. Inet bod of making concrete, is first to cover the foundation with a certainturned and ,' vater > and then to throw in the dry mixture of ballast and lime. It is nextis re Peated with shovels; after which more water is pumped in, and the operation

In s ome ’ , e former method is undoubtedly preferable,fixing clay 8 * 8 * 1 bas been found necessary to mix the ingredients in a pug-mill, as inln g should be' ^ c ' <s ‘ b' or the preparation of a concrete foundation, as the harden-a Perfect nj j xf ra P l( i» n0 more water should be used than is absolutely necessary to effect?bout one fifth 16 ^ ingredients. Hot water accelerates the induration. There isJngredients. °f contraction in volume in the concrete, in reference to the bulk of itse ct cube of nro ° j? a cu bical yard of concrete, about 30 feet cube of ballast and 3 J. CONopj-?„ a nd hme must be employed, with a sufficient quantity of water,nny means are ^ r^' ani ^ Fr- > Gefrierung , Germ.); the act of freezing liquids.0 not constitute su PP‘icd by chemistry of effecting or promoting this process, but theyDOLING Qj. ai iLPnculiar art or manufacture. See Ice-House.ten, a c nrrent of it * 1 . ■ Derosnes’s method, the cooling agents employed

Pcrature as tw ®°?Pb er ie air, and warm water of the same or nearly the same1 S- 295 represents ^ a P° r s which are to be operated upon.

merely a diagram of the general features of an apparatus con-