On 10/28/2013 5:29 PM, Dale Hooper wrote:
Hi Chuck,
I think a while ago you mentioned that Mike was silvering the mirror since it was too big to put in a chamber. When I was in high school I ground a mirror and I believe I used silver nitrate and hydrochloric acid in a process to silver the small mirror (I've forgotten most of the details - but I still remember "do what ya oughter - add the acid to the water. :)" ).
Not on the subject of astronomy, but your remark reminded me of an industrial accident a number of years ago. I had sold an 18' dia FRP tank for mixing HCL & water. A new employee filled the tank about 1/3, or more full of HCL, then opened a 6" water line into the tank. The mix started exotherming, and the employee was standing there listening to the whistling noise of the vent. A foreman rushed over, grabbed the employee, and ran to safety. The tank built up so much pressure inside that it blew apart at the knuckle (bottom joint at the floor). The base was bolted to concrete, so it stayed in place, but the tank shot up like a rocket, about a story and a half, where it made contact with a metal grating floor, and fell back to the floor, almost, but not quite, exactly on the base. Next tank had a 48" dia vent! A simple interlock system would have prevented it. 73