A Dictionary of Applied Chemistry, Volume 4

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Longmans, Green, and Company, 1922 - Chemistry, Technical
 

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Page 98 - KOH to produce a permanent pink with phenol phthalein on 6£ gms. of the dry powder suspended in water. If the acidity does not fall within these limits, it must be corrected by soaking the powder before chroming for...
Page 128 - There can scarcely be a doubt entertained respecting the reducibility of all elastic fluids of whatever kind into liquids; and -we ought not to despair of effecting it in low temperatures, and by strong pressure exerted upon the unmixed gases.
Page 97 - Sumach and myrobalans extracts should be dissolved at a lower temperature. Solid extracts shall be dissolved by stirring in a beaker with successive quantities of boiling water, the dissolved portions being poured into a litre flask, and the undissolved being allowed to settle and treated with further portions of boiling water. After the whole of the soluble matter is dissolved the solution is treated similarly to that of a liquid extract. Solid tanning materials, previously ground till they will...
Page 156 - So similar are the trees of the " true " and the " bastard " logwood, that it is frequently impossible to decide whether a tree is really a " mulatto " or not. When first cut a bastard tree is frequently dark enough internally to indicate that it is a good red-wood tree, but instead of darkening with age, as all the best wood does, it remains the same colour or becomes lighter rather than darker. Chemical tests readily distinguish between the red and bastard wood, for whereas alkaline solutions turn...
Page 98 - ... of water, and must be sufficiently free from soluble organic matter to render it possible in the ordinary washing to reduce the total solubles in a blank experiment with distilled water below 5 mgrs.
Page 68 - The brightening of pure silver at the moment of the separation of the last traces of lead, indicates the precise period at which the operation should be terminated, and the blast is then turned off, and the fire removed from the grate. The silver is now allowed to set, and as soon as it has become hardened, the wedges are removed from beneath the test which is placed on the floor of the establishment.
Page 61 - This type of furnace is usually made to hold from 8 to 12 tons of molten lead. The fireplace is about 20 inches wide, and has a length equal to the width of the cast-iron pan, from which it is separated by a bridge 2 feet wide. The height of the furnace above the pan at the bridge end is 16 inches, and at the other end 8 inches. The charge is introduced either in the form of pigs, or is first melted in an iron pot, set in brickwork, at the side of the furnace, and subsequently ladled into a sheet-iron...
Page 76 - The furnace-product is purified either by grinding finely and sifting, or it is water-ground, dried, and sifted. This variety is used for the production of paints, colours, printing inks, and enamels. The finest grades have a vivid orange tint. Orange lead differs from red lead, not only in colour, but also in bulkiness, size of grain, and in its behaviour towards linseed oil.
Page 98 - A further portion is now filtered in the exact method for which the correction is required (time of contact and volume rejected being kept as constant as possible) and 50 cc is evaporated to determine
Page 98 - ... cm. deep in a beaker placed in a good light on black glass or black glazed paper must appear dark and free from opalescence when viewed from above. Any necessary mode of filtration may be employed, but if such filtration causes any appreciable loss when applied to a...

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