1835.] Composition of Rangoon Petroleum. 527 



be clear, in order to constitute a change of weather. This may be arbitrary, but 

 at least it is not vague ; and if practised, it will prevent, in the balancing of 

 calculations, any leaning to a favorite hypothesis. To avoid another error, into 

 which some may have fallen, the author marks no change as occurring on lunar 

 phases, but those which take place on the very day, and never those which may 

 happen on the evening before or on the next day. With these precautions, he 

 finds that, during the thirty-four years, or 12,419 days, there have been 1,458 

 changes of weather. Of this number, 105 have taken place at the epoch of the 

 two principal lunar phases, viz. 54 at the new moon, and 51 at the full moon. 

 Now the whole number of principal phases during the thirty-four years is 840 ; 

 therefore, as 12419: 840 ;; 1458: 98 - 6, the number of changes which would 

 have taken place at new and full moon, had these lunar phases had no more 

 than the share of common days ; but instead of which, the number was 105. Of 

 the 54 changes at new moon, 32 were from rain to fine weather, and 22 from 

 fine weather to rain. Of the 51 at full moon, 31 were from rain to clear, and 20 

 from clear to rain. Thus at the new and full moon, the changes to fine weather 

 are to those to rain as 63 to 42. Having thus proved, that the epoch of new and 

 full moon are not absolutely without some effect on the weather, the author 

 examined, whether this effect was confined to those very days, or extended to the 

 day following. On the days following the new and full moon, there were 129 

 changes, instead of 98"6, which would have been the number had these shared 

 the proportion only of common days. With respect to the days of the first and 

 last quarter, the changes on these were 96, which bring them nearly to the 

 condition of common days. It is thus shown from the tables, that the chance 

 of change at the new and full moon, compared with the chance on ordinary 

 days, is as 125 to 117, and that the chance on the day following these two phases, 

 compared with the common days, is as 154 to 117. Upon the whole, therefore, 

 this examination lends some support to the vulgar opinion of the influence of 

 new and full moon, but none whatever to any special influence of the first and 

 third quarters. With respect to the barometrical pressure, it is ascertained, that 

 out of the 1,458 changes of weather, there were in 1,073 cases, a corresponding rise 

 or fall of the barometer, according as the change was from rain to fair or the 

 contrary. This is nearly as 3 to 4. Of the 385 false indications of the barometer, 

 182 were on a change from rain to clear, and 203 on a change from clear to 

 rain. Finally, of the 385 anomalies of the barometer, 17 were at full moon, 



and 10 only at new moon. 



2. — On the Composition of the Rangoon Petroleum, with Remarks on the Composi- 

 tion of Petroleum and Naphtha in general. By William Gregory, M. D. 

 F. R. S. E. 



The author first adverted to the discovery, nearly about the same time, of 

 paraffine by Reichenbach, and of petroline by Dr. Christison. The former 

 occurred among the products of destructive distillation ; the latter was found in 

 the Rangoon petroleum, and they were soon found to be identical. Reichenbach'9 

 researches on naphtha were then quoted, by which it appears, that that indefatigable 

 observer could not discover, in the kind of naphtha which he examined, any 

 trace either of paraffine, or of any other product of destructive distillation. On 

 the contrary, he found, naphtha to possess the characters of oil of turpentine, 

 a product of vegetable life ; and he succeeded in obtaining a precisely similar oil 

 from brown coal, by distillation at 212°. The facts had led Reichenbach to 

 3 y 2 



