Method of preventing Injury from White Lead , 453 
But the quantity they stretch before they break is in an- 
other proportion ; for that of the filaments of the aloe be- 
ing equal to two and a half; that of flax is only one-half; 
that of hemp one; that of the flax of New Zealand one 
and a half; and that of silk five. 2d, That great ad- 
vantages will result from the cultivation of the New 
Zealand flax in France, where it will thrive exceedingly 
well. 
No. 87. 
Description of a Method of preventing Injury to the 
Health of the Workmen employed in preparing White 
Lead . By Mr, Archer Ward. 
(With an engraving.) 
IN order to explain, as well as I can, the advantage 
that will accrue to the workmen by adopting my inven- 
tion, in preference to the common mode of preparing 
white lead, I will first state what the common mode is. 
When blue lead is in part corroded in the stacks, by an 
acid raised by a considerable degree of heat, brought on 
by horse-litter, the corroded and uncorroded lead are ta- 
ken from the stacks to a room called the engine-loft, 
where a pair of iron rollers is fixed with a screen under 
them. The lead in this state is passed through the rol- 
lers and screen ; from the motion of these rollers and 
screen, by which the white lead is separated from the un*> 
corroded or blue lead, together with the moving the lead 
in order to its being passed through them, a very consi- 
derable quantity of fine dusty white lead is raised, which 
* Repertory, vol. 5. p. 249. From the Transactions of the Society for the En° 
aouragement of Arts , &c . — The gold medal of the Society was voted to Mr. Ward 
for this invention. 
