Salt in 69 conducts 10.75 times better than salt in 999. Salt in 999 in tube 12; distilled water in tube 20. [R. = 494000.] El. = 21. 2 or 3 hours after it seemed rather greater at 5. Next morning was plainly greater at 7. The water being changed for fresh, seemed rather less at 3. Salt in 999 conducts 20 times better than salt in 20,000. Salt in 20,000 conducts about 7 times better than distilled water; therefore if distilled water contains 120000 of salt their conducting powers will be as the quantity of salt in them. Therefore salt in 999 conducts 19.5 times better than salt in 20,000. sensib. less. Salt in 999 conducts 19 times better than salt in 20,000. 2. sensib. less. Salt in 999 conducts 19.8 times better than salt in 20,000. Salt in 69 conducts 1.74 times better than salt in 142. Salt in 69 conducts 1.84 times better than salt in 142. Salt in 999 in tube 12, distilled water in tube 20. El. = 21. [R. = 494000.] N.B. The tubes had been measured between the last trial and this. The distilled water was then changed for fresh. 3 sensib. less. Another bottle was filled with distilled water and tube 20 filled up again with that. 631] The tube 20 filled with the same distilled water mixed with 200 of spirits of wine. Same mixture mixed with more of spirits of wine, id est, sp' wine in 18 of distilled water. Therefore there is not much difference between the resisting power of the above distilled water and spirits of wine and mixtures of the 2: but of the 2, spirits of wine resists least. After it was measured 7 inches were cut off from straight end, and the numbers in the first col. are the distances from the shortened end. A new bend was also made 12-8 from new end, and the part where the tube is equal to tube 14 is at 10.3 from D. 633] Jan. 1781. The following tubes were measured over again by introducing a col. and measuring its length in 3 different places, the beginning of the 1st col. being at inch from bend, and the beginning of the second at the end of the first. Another column was afterwards introduced whose length was pretty nearly equal to the sum of the 3 former, and weighed. 634] The two following tubes were measured by stopping up the end near bend and weighing them with different quantities of in them, and measuring the distance of the top of the column from straight eud, whence it was found that in 635] In the following result the column whose length is given in the 2nd column is supposed to begin at inch from the bend. By the resistance of each is meant 1 grains in each inch [The resistance of a column of mercury one inch long weighing one grain is 13 Ohms, and the resistance of saturated solution of salt at to Centigrade is to that of mercury as 10 is to 2015 + 45·1 (t − 18). Hence the resistance as given by Cavendish must be multiplied by 690782-2 (59-T) to convert it into Ohms when the tube contains saturated solution at To Fahrenheit.] COMPARISON OF RESISTANCE OF COPPER WIRE WITH THAT OF SAT. SOL 636] The wire was wound on reel on bars of glass about 2 inch broad, the distance of one round of wire from the next on same bar being 6. The mean circumference of reel = 46·7 × 2 √2*. There were 8 rows of glass bars, and 28 rounds of wire on each row, and on one row there was round over. Therefore whole length of wire = 93.4 × √2 × 8 × 28 + 1 = 29623 inches. * [The reel was probably square, with glass bars at the corners, the length of the diagonal being 46.7 inches.] |