Smithsonian Contributions to Knowledge Volume 34 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 Excerpt: ...being No. 9 with about 150,000 nuclei per cm3. Smaller electrometer factor. The average number of ions in those cases where positive and negative charges were observed are again found to be slightly larger than the preceding, due to further enlargement of the holes of the jet, whereby fresher nuclei are put into the condenser. The table states that the most advanced corona obtainable did not exceed the middle green-blue-purple type of my series,1 throughout the whole of the work. It makes little difference whether the corona is taken instantly or a few minutes after the jet is shut off. The number of nuclei therefore is constant throughout the experiments, being about io 13. Jets self-shattering or impinging on water.--To make sure preliminarily that no induced radioactivity is demonstrable within the limiting potentials to be employed, the experiments of the following table 10 were devised. Here the large vertical jet (No. 9, with 18 needle holes, discharging about 8 liters per mmute into the water below and violently churning it) was put in action, and the air above the water in the aspirator discharged into the condenser by the rise of level due to the jet. The table shows the insulation before and after the passage of nucleated air, for different potentials in the condenser. The data are given in centimeters of deflection per minute (ds/dt). Hence the currents are i=ds/dtX2Ax 10-amperes. 1 Phil. Mag (6), m, pp. 8o corrected in Am. J., xvi, 1903, P-35, and in Boltzmann's Jubelband, p. 204, 1904. Cf. Chap. VI. TABLE 10.-ABSENCE OP APPRECIABLE RADIOACTIVITY. VERTICAL JET NO. 9 IMPINGING ON WATER WITH VIOLENT CHURNING. 'Condenser at 80 volts in first row. Positive and negative charges follow charges of same sign during passage of nuclei. As it is the purpos...