2^S Dr. Priest LLi''s Experiments and ObJervatJons 



thing that I know to the contrary, the fame tube may ferve 

 for a very great number of proceffes, and perhaps the change . 

 made in the inlide furface may protect it from any farther adiori' 

 of the water, if the tube be of fufficient thicknefs ; but this- 

 can only be determined by experiment. 



Some eftimate of what may be expeded from this method of 

 procuring inflammable air may be formed from the following 

 obfervations. About twelve inches in length of a copper tube, 

 three-fourths of an inch in- diameter, filled with iron tuniings^ 

 (which are more convenient for this purpofe than iron flings^ as 

 they do not lie fo. clofe,. but admit the fteam to pafs through 

 their interftices-) when it was heated, and a fufficient quantity of 

 fleam pafled through it, yielded thirty ounce meafures of air in 

 fifty feconds ; and eighteen inches of another copper tube, an 

 inch and a quarter in diameter, filled and treated in the fame 

 manner, gave two hundred ounce mealures in one minute and 

 twenty-five feconds ;. {q> that this lai^ger tube gave air in pro- 

 portion to its folid contents compared with the Imaller ; but to 

 what extent this might be depended upon I cannot tell. How- 

 ever, as the heat penetrates fo readily to fome dlftance, the rate 

 of giving air will always be in a greater proportion than that of 

 the limple diameter of the tube. 



The following experiment was maxie with a view to afcertain 

 the quantity of inflammable air that may be procured in this 

 way from any given quantity of iron. Two ounces of iron^ 

 or 960 grains, when diflblved in acids,, will yield about 80a 

 ounce meafures of air ; but treated in this manner it yielded 

 1054 ounce meafures, and then the iron had gained 329 grains 

 in weight, which is little fhort of one-third of the weight of 

 the iron. 



Confiderlnj^ 



