A Few Popular Facts About Diffusion. 41 



average total heating surface is about 820 square feet per 

 boiler. For every pound of coal we burn, we evapo- 

 rate 8*53 lbs. water from and at 212 deg. Fahr. to mean 

 gauge pressure, and the average horse power of each of 

 these coal boilers is 54 h.p. on the basis of one cubic 

 foot of water evaporated per hour. 



We use generally the same number of chip boilers 

 (viz : six) every day. Their average total heating surface 

 is about 1,083 square feet per boiler, and the average 

 horse power of each chip boiler is 75.7 h.p. on the basis 

 of one cubic foot of water evaporated per hour. 



From the above figures (even if we only get chips 

 enough for five chip boilers, which is sometimes the case) 

 you can readily see that while our coal used does only 

 47 0/0 of the work, our chips do 53 0/0 of the total work 

 of the Diffusion Fa6lory. These figures are very signifi- 

 cant, and can be left to speak for themselves. 



If you attempt to make paper-stuff out of exhausted 

 slices, or megass, in order to make such manufa6lure pay, 

 you must produce a good quality of " stuff," such as will 

 fetch good market prices ; and the latter at the very out- 

 set demand a length of fibre of at least half an inch in 

 length. This requirement appears altogether incom- 

 patible with a good diffusion-slice barely one-sixteenth 

 of an inch thick, and at once shuts the door on this ex- 

 pe6led outlet, independently of several other serious 

 obje6lions, which for want of time cannot even be touched 

 upon in this paper. In dealing with this special question 

 I am speaking from considerable experience, having been 

 in charge of experiments made in this colony with a view 

 to making paper out of double-crushed megass. 



In the case of the old process you have, we will say, 



F 



