Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . lar to that seen in fig. 1, and in adding aquantity of mineral tar, iu the proportion of1 lb. to every cwt. of the mastic. The tar isfirst fused in the boiler, 56 lbs. of the masticare then introduced, and the whole repeatedlystiried so as to prevent the format
Cooley's cyclopaedia of practical receipts and collateral information in the arts, manufactures, professions, and trades including medicine, pharmacy, hygiene, and domestic economy : designed as a comprehensive supplement to the Pharmacopoeia and general book of reference for the manufacturer, tradesman, amateur, and heads of families . lar to that seen in fig. 1, and in adding aquantity of mineral tar, iu the proportion of1 lb. to every cwt. of the mastic. The tar isfirst fused in the boiler, 56 lbs. of the masticare then introduced, and the whole repeatedlystiried so as to prevent the formation of adeposit. When the contents of the boiler aremelted, the cauldron is covered over for aquarter of an hour, after which the remainderof the mastic is added, and its fusion pro-ceeded with as before, the process being re-peated until the boiler is full, allowing an in-terval of from ten to fifteen minutes betweeneach operation. When the mastic is sufficiently fluid it willdrop freely from the stirrer, and jets of lightsmoke are observed to issue from it. If stiffmastic be required, the proportion of tar islessened, and a quantity of coarse grit or riyersand, to the amount of 20 or 30 lbs, to thectot., is added. tlie bed of coarse concrete, B the second andfiner layer of the same material, and A thesuperior layer of In laying the asphalt the greatest atten-tion and care must be paid to the preparationof a solid and dry foundation. This is usually accomplished by removingor ramming the loose earth, and placing uponthe bed a layer of coarse sand mixed withpowdered limestone, in the proportion ofseven parts of the former to one of the latter,and the whole is pressed or beaten solid;upon this a second layer of finer materials islaid compacted and levelled; the bed thusprepared is allowed to dry before coating itwith mastic. Fig. 2 shows the manner in which ordinaryasphalting is laid down. In this figure c is
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