Page:A Letter on the Subject of the Cause (1797).djvu/27

 but any Fat which may be the moſt readily procured, and there are certainly ſome which if applied would be injurious both to Engine and Keeper.

This is ſucceeded by the ne plus ultra of abſurdity. It is directed to uſe quickſilver, and other metals in their fluid ſtate. Quickſilver, my Lord, would amalgamate, and incorporate with all the parts of an Engine which are neceſſarily of braſs, and preſently crumble them to powder. Beſides when the Engine received a denſe, and overheated ſteam, the Mercury would diſſipate in fumes and poiſon every living creature in its vicinity.

Before I proceed to denote the effects of melted Metals applied in their fluid ſtate, it may be neceſſary to remark for your Lordſhip’s information, that the piſton of all Newcomen’s Steam Engines, and of thole alſo made by Mr. Watt, are firſt packed and made ſteam tight with hemp, tow, junk, or ſome ſoft ſubſtance ſaturated with melted tallow; and then water always kept on the ſide of the piſton where the force of the ſteam, or air, acts, in order to render it more perfectly tight than it could be made and