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Commercium philosophico-technicum, or, the philosophical commerce of arts : designed as an attempt to improve arts, trades, and manufactures / by W. Lewis
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bishop of London’s garden at Fulham, after having beenlong neglected, and suffered many severe winters: fee acatalogue of the exotic trees in this garden, by Dr. Watson,in the Philosophical Transactions, vol. 47, for the years1751 and 1752. They appear also to perfect their co-louring juices, in this, nearly as well as in their native cli-mate. The species called by Mr. Miller the true lac tree,of which I was favoured with a branch by himself fromChelsea garden, was found to contain, in its bark, and inthe pedicles and. ribs of the leaves,,a somewhat milky juice,which soon changed in the air, to a reddifh-brown, and intwo or three hours to a deep blackish or brownifh-blackcolour: wherever the bark was cut or wounded, the in-cision became blackish; and on several parts of the leavesthe juice had spontaneously exuded,, and stained them ofthe same colour. This juice,, dropt on linen, gave at firstlittle or no colour, looking only like a spot of oil; but bydegrees the part moistened with it darkened in the samemanner, as the juice itself. On washing and boiling thelinen with soap, the stain not only was not discharged, butseemed to have its blackness rather improved; as if abrown matter, with which the black was manifestly de-based, had been in part washed out, so as to leave theblack more pure.

It were to be wished that some attempts were made, forcollecting the colouring juices of these trees, in. sufficientplenty, for answering the important purposes to whichthey promise to be applicable. Perhaps also means mightbe found of introducing- into some parts of the extensivedominions of'Great-Britain, in which all varieties of soiland climate are now to be met -with, the oriental treesthemselves, to which some of the Indian manufactures aresupposed to owe distinguished advantages. This thereare now.some grounds to hope for, from the patronage os a

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