place sí circumference into 17 parts. The arc 1 1 1 is one of these parts; the continued line 1 1 1 is equal to the central diameter 10 i. 17 17 17 17 16 17 52 53) 54) quations Now this central diameter is a unit; for the central circle and its diameter are respectively units, which are heterogeneous with each other. All the parallel lines, 111, 111, &c. are equal to this 1 0 1 2 1 2 last unit. These lines are the greatest which can be drawn between the two extreme circumferences of each ring, and they may be considered as the diagonals of those rings, in the same manner as the diameter 1 0 i can be considered as the diagonal of the central circle. We have, then, between the diagonal of the central circle and the diagonal of the rings, the same analogy as between the central circle itself and these rings; the central circle and the rings are both superficial units, and maxima ; the diagonals of the central circle and of the rings are both linear units, and also maxima: This geometrical construction of the problem, as presented by fig. 1, is the only one which can be right; because all the straight lines of this figure are either maxima or minima, in such a manner that if they be maxima as lines, they are minima as being opposite to an angle or an arch which is a minimum; and if they be minima as lines, they are maxima, as being opposite to an angle or an arch which is a maximum, as I shall demonstrate at length in another paper. These lines, then, cannot be greater or less than they are. M. le Gendre, at the end of his Geometry, has given an algebraical solution of this problem, but he has not given the geometrical construction of his formulæ : that construction was in fact impossible, without destroying the law of continuity. es of 185 he are of two do a ARTICLE III. 1. After having in 1796 discovered a method of obtaining pure malleable nickel by means of an oxygen gas fire, either from Freiberg Bleispeise, or from the common regulus of nickel obtained from copper nickel by the usual process, I occasionally made a nůmber of accurate experiments on many of the properties of this metal, which had been hitherto examined only in a cursory manner. 124 grains of speise gave me 43 grains of nickel, and 123 grains of copper nickeł ore gave me 63 grains of the pure metal. whic 2. Magnetic Power of Nickel. The magnetometer described in the preceding paper gave the * Translated from Schweigger's Journal für Chemie und Physik, x. 174. 1814, a con ferest ed like des the a magnetic energy of nickel = 35, and that of iron = 55. The magnetic energy of cobalt was likewise tried, and found = 25; but as this metal was not quite pare, this experiment, as well as the magnetism of an alloy of cobalt and nickel, will be hereafter repeated. 3. Alloy of Nickel and Platinum. This, as well as all the subsequent alloys, was made upon charcoal kept intensely hot by a stream of oxygen gas, according to the method described in my Manual for the Analysis of Minerals. A grain of each of the two bodies, nickel and platinum, was put upon the charcoal. After they had been softened by the application of the heat for about half a minute, both bodies incorporated together in a very striking manner. They formed an alloy possessing nearly the fusibility of copper, although nickel by itself is nearly as infusible as platinum. The alloy was completely malleable, acquired a fine polish, and had a light yellowish-white colour, not unlike that of sterling silver. Its magnetic energy was still 35. 4. Gold and Nickel (equal parts). Both metals very readily melt into one round button ; pretty hard, harder than the preceding alloy ; externally malleable ; capable of a fine polish; colour yellowish-white, a little darker than the preceding alloy. The magnetism continued = 35. 5. Silver and Nickel (equal parts). When I attempted to alloy these two metals, I made the following observations." The silver melted in two seconds, and the nickel remained for some time unmelted upon the silver. In about a minute the silver, it is true, took up the nickel, but did not dissolve it. When the heat was continued some time longer, the two metals appeared to unite ; but at that instant the silver burnt away : with a blue flame, and left the malleable nickel behind it; but about one half of the nickel likewise was burnt. 6. Copper and Nickel (equal parts). Both metals melted together in four seconds. The alloy was brittle and granular; the colour reddish-white; and the fracture porous. It exhibited no trace of magnetism. 7. Nickel and Iron. Iron and nickel easily melted together into a round bead. The nickel was first melted, and the iron added to it, to prevent the last metal from being burnt by the heat. By continuing the heat, the greater part of the iron separated from the nickel in the state of a black oxide, still attracted by the magnet. By weighing the alloy I found that it consisted of ten parts of nickel and four parts of iron, or the iron amounted to rather less than one-third of the alloy, This alloy was moderately hard, quite malleable, and had the colour of steel. Its magnetism was = 35. 8. Phosphorus and Nickel. The bead of nickel was heated red-hot, and then a small piece of phosphorus placed in contact with it. They melted together in a few seconds. 34 parts of nickel thus treated increased in weight five parts ; so that 100 nickel had combined with 15 phosphorus. The button externally was tin-white, and had the metallic lustre, It was moderately hard, and very brittle. Its fracture was foliated and crystalline, partly dull, and partly with the metallic lustre. Its magnetism was gone. 9. Nickel and Sulphur Easily united together, when treated in the same way as the nickel and phosphorus had been. Externally the button was dull, swelled, and grey in colour. Its magnetism likewise was gone. 20 parts of nickel had taken up two parts of sulphur; so that 100 of the metal combine with 10. The mass was elastic, not very hard, the fracture uneven, and the colour yellowish-white, similar to that of native copper 10. From these experiments we learn, a. The readiness with which nickel and platinum unite together, 1. The little affinity between silver and nickel, as the silver rather combines with oxygen and is dissipated, than remains united to the nickel. 6. The singular effect of combining it with copper, in which we see two malleable metals produce a brittle alloy. d. The permanence of the magnetism of nickel when it is alloyed with gold and platinum. e. Its complete destruction when nickel is alloyed with copper. f. Its diminution when nickel is alloyed with iron. Perhaps a farther prosecution of these experiments might have a tendency to throw some light upon magnetism. At present I lay aside all hypotheses, and satisfy myself with stating simple facts. nickel ore. a ARTICLE IV. 1814. IC Nov. 18_h_ _" 1h 40' 24° 19' 59" 35 24 26 10 33 (1814. West. } ..,.. Ditto 8 47 .... Mean of (Morning Observations Noon in Nov. Evening Morning Ditto in Oct. Noon Evening Morning Ditto in Sept. Noon Evening Morning Ditto in Aug. Noon Evening Moruing Ditto in July, Noon Evening Morning Ditto in June. Noon Evening Morning Noon Morning Noon Morning Evening Morning Noon Morning Evening 1813. Morning Diaw in Dec. Noon Evening Morning Noon Morning Noon Morning Noon Morning Evening Morning Ditto in July. Noon Evening at 8h 41'..... Variation 24° 16' 20" 40 Ditto 24 20 37 Not obs. Ditto West. Not obs, 8 32 Ditto 24 14 33 West. 6 57 Ditto 24 16 31 24 13 29 at 1 42 Ditto 24 23 44 West. at 6 58 Ditto 24 17 00 8 44 Ditto 24 13 10 24 22 48 West. 24 16 29 Ditto 24 13 12 at 1 44 Ditto 24 22 13 West. 6 38 Ditto 24 16 14 West. 24 23 08 Ditto West. Not obs. West, Ditto 24 19 03 Not obs. West. 20 30 Not obs. West. at 54 Ditto 24 20 24 ) Not obs, West. 59 Ditto 24 22 53 ] Not obs, 53 Ditto 24 15 46 02 West. 24 16 04 at 44 Ditto 24 15 55 02 at Ditto 24 23 32 West. 16 08 Ditto 24 14 32 Ditto 24 23 04 West. 24 12 55 05 } 32 24 Morning Noon Morning Evening Morning Hitto in April. Noon Evening Ditto 04 Ditto 24 16 04 at 8 293 Ditto 24 12 02 Ditto 24 13 47 24 09 18 at 59 Ditto West, 24 21 12 at 5 46 ..... Ditto 24 15 25 In tali kusually mening & Dec. 11 gh '45' 24° 18' 52" h 1 1 40 24 20 01 1 20 24 19 59 Comparison of the Variations in the Years 1813 and 1814. April May June July Morning Evening. Noon... Noon... Evening. Aug. Sept. + Oct. Nov. In taking the mean of the observations for the month of November, the variation on the 4th and 25th are rejected, as being unusually great, for which no cause can be assigned Dec. 9. The needle vibrated at intervals 26' 20''; and in the evening the wind blew very hard and squally from the S.W. accompanied by rain. Vol. V, N° 1. E |