( 2 55 > ) 
hardefl Stones and Marbles require more chafing or 
heating than others, 3nd that the fame Rule obtains 
with regard to the Woods • fo that Box, Lignum 
Vittf, and fuch others mufl be chafed almoft to the 
Degree of burning, whereas Fir y Lime-Tree and 
Cork , require but a moderate Heat. 
Secondly , Having read in one of Mr. Gr^/s Let- 
ters, that Water may be made Electrical 
by holding the excited Glafs Tube near ^l l °/ z J ra ^ 
it (a Difh of Water being firft fix’d to a * P * 22 '* 
Stand, and that fet on a Plate of Glafs, or on the 
Brim of aDrinking-Glafs, previoufly chafed, or other- 
wife wanned) I have found upon Trial, that the fame 
thing happen'd to allBodies withoutException.whether 
folid or fluid ^ and that for that Purpofe *twas fuffici- 
ent to fet them on a Glafs-Stand flightly warm’d, or 
only dried ; and then by bringing the Tube near them, 
they immediately became Electrical. I made this 
Experiment with Ice, with a lighted Wood-coal, and 
with every thing that came into my Mind $ and I 
conftantly remark'd, that fuch Bodies as of themfeives 
were leaft Eledrical, had the great-eft Degree of Elec- 
tricity communicated to them at the Approach of the, 
Glafs Tube. 
Thirdly , Mr .Gray fays, towards the End of one 
of his Letters, that Bodies attraCi more 
or lefs according to their Colours. This 
led me to make feveral very Angular 
Experiments. I took nine (ilk Ribbons of equal Size, 
one white, one black, and the other feven of the feven 
primitive Colours, and having hung them all in Or* 
der on the fame Line, and then bringing the Tube 
near them, the black one was firft attrafted, the wr ite 
