380 , PHILOSOPHICAL TKANSACTIONS. [ANNO 1699- 



sary for curing a delirium and fever, that whatever effect the applying of vast 

 numbers of blisters over all the body may have, yet the main end is neglected if 

 we omit a large one on the upper part of the nape of the neck. 3. That when 

 there is no vesication after laying on a strong plaister, it necessarily causes a 

 new and extraordinary hardness in the skin and vessels, and a thickening of the 

 blood for a further and total stoppage. 



On the Nature and Qualities of Silk. By If'illiam Aglionby, Esq. F.R.S. 



N° 252, p. 183. 



Silk, which is the spittle* of a worm, has its good or bad qualities from the 

 nourishment the worm receives from a good or bad leaf. 



When the spring proves agreeable, the worm feeding on a good and tender 

 eaf, free from the prejudices of an unkind season, which sometimes spoil the 

 leaf, by giving it a gross nature, then one may expect a profitable harvest. 

 About Midsummer they begin in Piedmont to draw the silk from its cocon, to 

 see what it yields, and judge of its increase or scarcity, as well as the estimate 

 of its qualities, which are, being clean, light, and strong. 



With respect to the silk, its goodness is most distinguished by its lightness: 

 for the organzine is the best sort. It must be observed that the two threads are 

 equal in fineness, that is, both alike in smoothness, thickness, and length, for 

 the thread of the first twist ; for the second, it matters not whether the single 

 thread be strong, before the two are joined, unless to see whether the first 

 twist prove well. It is necessary the silk be clean ; the straw colour is commonly 

 the lightest, and the white the heaviest. It is likewise convenient that the 

 skains be even and all equal, which shows they were wrought together. 



Tivo Propositions desired to be answered in a Year and half by any Person ; if 

 they are not ansivered in that Time, the Proposer provjises hezvill do it himself. 

 N°252, p. 186. 



1st question. — Dato nascente vegetabili quolibet a nascendi modo, ejusdem 

 cohaerendi nisus, seu partium ejusdem mobilitas ac immobilitas, determinari 

 possunt ? 



2nd question. — An esse possit signum aliquod, et quidnam sit illud, quod ex 

 anatomia, ac cadaveruin dissectionibus, certo poterit indicare quemlibet ob as- 

 sumptum opium interemptum fuisse ? 



* The term spittle is improper. The glutinous fluid from which silk is producedj is secreted in 2 

 canals which run along the back of the worm, and alter making several sinuosities near the ston:ach 

 terminate at the mouth by an extremely slender duct (or according to some naturalists by 2 ducts) 

 from which this peculiar fluid is discharged by the muscular efforts of the worm in the act o spinning. 



