The Science record; a compendium of scientific progress and discovery . cent ores, $, equal to 3fcents a pound. The cost of the plant required is small. The furnacesare simple and inexpensive in construction, and requireabout 25,000 bricks each. The tanks cost, complete, about$60 each, and the labor employed neednot be skilled or high-priced. THE JACKSON B. Pennington presents to thephoto fraternity, through the Philadel-phia Photographer, a new plate dipper,which is evidently a most useful littleaffair. He dedicates it to the public,not intending to secure it by bod
The Science record; a compendium of scientific progress and discovery . cent ores, $, equal to 3fcents a pound. The cost of the plant required is small. The furnacesare simple and inexpensive in construction, and requireabout 25,000 bricks each. The tanks cost, complete, about$60 each, and the labor employed neednot be skilled or high-priced. THE JACKSON B. Pennington presents to thephoto fraternity, through the Philadel-phia Photographer, a new plate dipper,which is evidently a most useful littleaffair. He dedicates it to the public,not intending to secure it by body A he makes out of hickory,covered with shellac. At C it is curved,to keep the plate at a proper distancefrom the handle. B is a silver slide,which moves up and down on the han-dle so that any size of plate may beheld. One special advantage of thisinstrument is, that plates may be placedin the bath back up; floating particlesof dirt are thus prevented from injuringthe film, which leaves the bath who love good work will findthis dipper to be of TECHNOLOGY. 173 THE MANUFACTURE OF PLASTER-OF-PARIS. By J. F. Gesner, —Gypsum is a mineral very widelyand abundantly disseminated, whether as the snow-white,translucent, and massive alabaster, the transparent, crys-tallized selenite, the fibrous, beautiful satin-spar, or theordinary amorphous, rather soft plaster-stone. It is .onlywhen ground and calcined that the term plaster-of-Parisis applied to it, from the great extent of gypsum existingat Montmartre, near Paris, where it has been worked for along time.
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Keywords: ., bookcentury1800, bookdecade1870, booksubje, booksubjecttechnology
