Journal - Franklin Institute of the State of Pennsylvania (1826)
Franklin Institute, Philadelphia, Franklin Institute (Philadelphia, Pa.) · [Philadelphia : Franklin Institute] · leaf 53
s placed, but this drillmakes about thirty-five hundred revolutions per minute. Corundumor diamond-dust and oil is put into the countersink opening in theiridium, and then it is held up against the piece of revolving copper.The diamond-ilust or corundum, imbedding itself in the copper, actsas a… … means of nitric acid; and then we have irregular-shaped pieces ofiridium, pierced with holes. These pieces of iridium are then solderedin proper position to the end of the Mackinnon pen, fitting into theopening of which there is a valve consisting of an iridium-pointed wire.The iridium is then…
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