Diseases of the soft structures of the teeth and their treatment; a text-book for students and practitioners . ll, while the sledge induction coil may be fedfrom a series of batteries, or from the streel current reduced by arheostat. The small induction coil with one dry cell battery givesuniversal satisfaction and on account oi it- cheapness, simplicityand easy transportation deserves to he recommended. More com-plicated types of apparatuses may be obtained from electric ordental supply houses. The induction coil produce- a secondary current in a circuit placed near to. hut not in contact wit
Diseases of the soft structures of the teeth and their treatment; a text-book for students and practitioners . ll, while the sledge induction coil may be fedfrom a series of batteries, or from the streel current reduced by arheostat. The small induction coil with one dry cell battery givesuniversal satisfaction and on account oi it- cheapness, simplicityand easy transportation deserves to he recommended. More com-plicated types of apparatuses may be obtained from electric ordental supply houses. The induction coil produce- a secondary current in a circuit placed near to. hut not in contact with, the galvanic field. This galvanic field, the primary current, i- repre-sented l>\ three or four layers of coarse wire wound about a hollowDon-conducting cylinder, and the two ends of which are united DIAGNOSIS OF DISEASES OF THE DENTAL PULP 81 with the binding posts. Within the cylinder is found a core of softiron rods, which are covered in the simple induction coil bv amovable brass tube (the tube of Duchenne). Outside of the coreand the primary current is a second coil, usually consisting of a or*. 50.—Columbia pulp tester and ionization apparatus. (Wall model.) great many turns of fine popper wire. The ends of this coil are alsoconnected with the bmding posts. When the current from the cellpasses through the coil of coarse wire-the primary current-acurrent ,s also mduced in the secondary coil of hue wire becausethe passage of the primary current makes the iron core strongly 82 DISEASES OF THE DENTAL PULP magnetic. A vibrator is placed in close proximity to the iron the current passes through the primary coil and becomesmagnetized, the steel spring of the vibrator is attracted and breaksthe <iirmit. The magnet is now immediately released and thespring reasserts itself. The control of the current is guided bymoving the brass tube; the gradual removal of the tube incnthe current and vice versa. To furnish an approximate guide ofthe strength of the current,
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Keywords: ., bookcentury1900, bookdecade1920, bookiddiseasesofso, bookyear1922
