. The Dental cosmos. good or evil results inalloys, and pointed out ways and meansof correcting the vital faults appearingas he proceeded with his work. His planwas to devise instruments for measuringthe movements of amalgams in setting,and to ascertain the strength of the finalproducts. These instruments were sci-entifically built, and unquestionably workmost accurately of any yet made for thispurpose. His micrometer (see Fig. 1)is so constructed that the slightest changein volume, expansion or contraction, can ally see the change which has taken work throughout was of the mostac
. The Dental cosmos. good or evil results inalloys, and pointed out ways and meansof correcting the vital faults appearingas he proceeded with his work. His planwas to devise instruments for measuringthe movements of amalgams in setting,and to ascertain the strength of the finalproducts. These instruments were sci-entifically built, and unquestionably workmost accurately of any yet made for thispurpose. His micrometer (see Fig. 1)is so constructed that the slightest changein volume, expansion or contraction, can ally see the change which has taken work throughout was of the mostaccurate and painstaking character, andup to this date no one has succeeded indisproving any of his conclusions. Theresults of the following experiments,which were made in Dr. Blacks labora-tory, conform in every point with hisconclusions, and only tend to emphasizetheir accuracy. (See Figs. 2-5.) EXPERIMENTS. Weighing of metals. The metals usedin each melting were carefully propor-tioned and weighed to the accuracy of. be measured, even to the 1/20,000 of aninch. With this instrument minutemeasurements can be taken with the samedegree of accuracy that the mechanic canmeasure the half-inch or the Black also made a matrix with whichfillings could be made of uniform size inthe form of a cube. He also built theamalgam dynamometer with which lietested these small fillings (which were85/1000 of an inch in size) for strengthin pounds. To the dynamometer a smallmicrometer is attached, with a scale madeof units of one-thousandth of an instrument registers the flow undera given pressure within a given binocular microscope was used toverify the work of the micrometer. Inall cases where the micrometer indicatesshrinkage or expansion in any marked de-gree, this microscope enables one to actu- 1, 64 of a grain. The amount made upeach time varied from 10 to 30 grams,depending upon the different tests de-sired. Alloying. The following is Dr. Blackslatest stateme
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentist, bookyear1912
