62-42 Much employed in dyeing and calico printing. Used in calico printing. Insoluble. Usually called white lead. Sugar of lead, used in dyeing and calico printing. Patent yellow; is a mixture of chloride and oxide of lead. Blue vitriol, employed as an escharotic. Crystals of a bluish green color. Crystallizes in four-sided prisms. Deliquescent. 91-78 Crystallizes in rhomboidal prisms with shining lustre. 265 2 170.5 Corrosive sublimate-dangerous. Darkens when exposed to light. Common marking ink is O'N + O Pb 165.9 151.8 O°C + O Pb 133.82 163-18 274-88 93.9 O3N + O Cu 79.8 A + O Cu 91.18 05 N + OZ 94.5 03N + OZ 80.4 251.1 Cl2 Hg 274 O' N + O Ag RECIPE FOR DYEING HATS. The bath for dyeing hats, employed by the London manufacturers, consists, for 12 dozen, of 144 Pounds of logwood; 12 66 71 green sulphate of iron or copperas, The copper is made of a semi-cylindrical shape, and should be surrounded with an iron jacket, or case, into which steam may be admitted, so as to raise the temperature of the interior bath to 190° Fah., but no higher; otherwise the heat is apt to affect the stiffening varnish, called the gum, with which the body of the hat has been imbued. The logwood having been introduced and digested for some time, the copperas and verdigris are added in successive quantities, and in the above proportions, along with every successive two or three dozen of hats suspended upon the dipping machine. Each set of hats, after being exposed to the bath, with occasional airings, during 40 minutes, is taken off the pegs, and laid out upon the ground to be more completely blackened by the peroxydizement of the iron with the atmospheric oxygen. In 3 or 4 hours the dyeing is completed. When fully dyed, the hats are well washed in running water. A skilful operator furnishes the following valuable information relative to the stiffening of hats. He says: All the solutions of gums which I have hitherto seen prepared by hatters, have not been perfect, but in a certain degree a mixture, more or less, of the gums, which are merely suspended, owing to the consistency of the composition. When this is thinned by the addition of spirit, and allowed to stand, it lets fall a curdylooking sediment, and to this circumstance may be ascribed the frequent breaking of hats, My method of proceeding is, first, to dissolve the gums, by agitation, in twice the due quantity of spirits, whether of wood or wine, and then, after complete solution, draw off one half the spirit in a still, so as to bring the stiffening to a proper consistency. No sediment subsequently appears on diluting this solution, however much it may be done. Both the spirit and a kali stiffenings for hats made by the following recipes, have been tried by some of the first houses in the trade, and have been much approved of: Spirit Stiffening.-7 pounds of orange shellac; 2 pounds of gum sandarac; 4 oz. of gum mastic; pound of amber resin; 1 pint of solution of copal; 1 gallon of spirit of wine, or wood naphtha. The shellac, sandarac, mastic, and resin, are dissolved in the spirit, and the solution of copal is added last, Alkali stiffening.—7 Pounds of common block shellac; 1 pound of amber resin; 4 oz. gum thus; 4 oz gum mastic; 6 oz. borax; pint of solution of copal. The borax is first dissolved in a little warm water (say 1 gallon); this alkaline liquor is now put into a copper pan (heated by steam), together with the shellac, resin, thus, and mastic, and allowed to boil for some time, more warm water being added occasionally until it is of a proper consistence; this may be known by pouring a little on a cold slab, somewhat inclined, and if the liquor runs off at the lower end, it is sufficiently fluid. If, on the contrary, it sets before it reaches the bottom, it requires more water. When the whole of the gums seem dissolved, half a pint of wood naphtha must be introduced, with the solution of copal; then the liquor must be passed through a fine sieve, and it will be perfectly clear and ready for use. This stiffening is used hot. The hat bodies, before they are stiffened, should be steeped in a weak solution of soda in water, to destroy any acid that may have been left in them (as sulphuric acid is used in the making of the bodies). If this is not atter ded to, should the hat body contain any acid when it is dipped into the stiffening, the alkali is neutralised, and the gums consequently precipitated. After the body has been steeped in the alkaline solution, it must be perfectly dried in the stove before the stiffening is applied; when stiffened and stoved, it must be steeped all night in water to which a small quantity of the sulphuric acid has been added; this sets the stiffening in the hat body, and finishes the process. A good workman will stiffen 15 or 16 hats a day. If the proof is required cheaper, more shellac and resin must be introduced. TABLE Of Pressures at which certain Gases are Liquified. Gas is the name given to those elastic fluids which are permanent under a considerable pressure, and at the temperature zero. TABLE Showing the Proportionate Strength of Wheels in Horse Power, with a Velocity of 2.27 Feet per Second. Formula 32.25 x 43 5 = 117.60 strength, at 2.27 feet per second Ft. per Strength Ft.per sec. in H. P. sec. 934-74 Then as 2-27: 117 60 :: 5:259′9 h. p. The thickness of cog multiplied by 6.7253.25 43.5 39 117.60 259.9 518.00 776.2 1031 27 12954 1558.6 45.33 39.35 34.60 30.56 25.58 6:56 3.125 42.6 3.75 110.95 244 38 488.7 17.70 38.10 732 7 977 00 1221.9 1466.7 675.66 900.00 112606 1352-2 21:33 46.70 93.50 135.90 77.00 |