GASES, SOUNDS PRODUCED BY. In our article Aeous vol. i. we have mentioned the experiments by Dr Chladni, on the sounds of different degrees of acuteness produced by the same organ-pipe, when blown with differ ent gases, in appropriate receivers ; and in page 115 we stated that the number of vibrations which the same column of gases of different specific gravities should make in a given time, are inversely proportional to the square roots of their specific gravities.
We propose, in the present article, to exhibit, in a tabu lar form, the results of the principal experiments that are recorded on this subject, for comparison with calculations on the above principles, and with other calculations from the velocities with which sound is propagated through dif ferent gases, considering the pitches of the sounds to be in versely proportional to the velocities of propagation.
In the first column of our table are mentioned the names of fifteen kinds of gases, on which Messrs F. Kirby and Arnold Merrick made repeated experiments, which are fully detailed, and their apparatus described, in Nicholson's Philosophical Journal, vol. xxxiii. p. 171 ; and in the second and third columns arc set down the mean results of these several experiments, as they have been calculated by Mr John Farey, in the Philosophical Magazine, vol. xlv. p. 28. The intervals in column 2. being stated in his notation, (as usual in other parts of our work,) reckoned upwards and downwards from note C, to which the experiment pipe in atmospheric air is supposed to be accurately adjusted. Co lumn 3. shews the nearest notes on the Rev. Henry Lis ton's Organ, (see that article,) followed by the differences, whether more acute +, or grave —, ex pressed in Schismas; small and capital Italic letters mark ing the octaves, above and below C c.
In column 4, the specific gravities of the gases have been taken from the mean of those mentioned in our article CHEMISTRY ; and column 5, (like col. 2.) shews the calcu lated intervals above and below C; wherein it will be ob served, that ether vapour, and sulphuretted hydrogen, ap pear to be graver notes than C, and olefiant gas more acute than it, contrary to the results of experiments thereon in col. 2.
In column 7. are contained the velocities with which sound is propagated, extracted from ACOUSTICS, Vol. I. p. 118 ; in col. 8. are the intervals ; and in columns 6. and 9. the several notes and differences, as already described.
By subtracting the intervals in columns 2, 5, or 8, (with due attention to the signs,) the relation or interval of any two gases may be found, and the name of such interval may often be obtained from our 30th Plate, in Vol. II. Thus, in the experiments in col. 2, hydrogen appears to yield a sound higher than azote by 610 E + 12 f + 53 m, or only 1.49 E less than an octave. Again, the interval of azote and oxygen, in col. 5. is 55.29E+f+5 m, or S-1.71 E ; and be tween the sounds of oxygen and olefiant gases, is 55.70E+ f+5 m, or S-1.3E, &c.
The Table here presented will at least serve to shew, that much remains to be done, to reconcile the facts and the principles that have been advanced by different writers on the subject. Careful and numerous repetitions of these
experiments, with gases carefully prepared, and in well contrived apparatus, conducted as Mr Farey has recom mended, with reference by means of the beats, to fixed notes, carefully tuned on Liston's organ ; not trusting to unisons for the comparisons of the sounds in any case, but resorting to the thirds and filths by way of checks: Experiments so conducted might, perhaps, so adjust these several intervals, that they may prove of use, in giving greater precision and consistency to the specific gravities, velocities of propagated sounds, and perhaps to the weights of atoms also, of the several gases ; if it be true, as has been conjectured, (and, as seems nearly true of most of the gases in our Table, and perhaps of others,) that, with excep tion of oxygen and olefiant gases, the weights of atoms, nearly as stated by Dr Thompson in his Annals of Philoso phy, are exactly double (or octave) of the specific gravities, respectively, (to oxygen, 1.); but nitrous gas seems here to form a remarkable exception, as Dr Chladni found it to present, on another point, in his experiments, as mentioned in our first volume, p. 115. It may not be amiss to add, that the specific gravity of nitrous gas being 1.094, its note will be C'-3.63E=39.631+ f+3 in, below C, according to the principle of calculation used in our Table ; whereas in Messrs Kirby and Merrick's first set of experiments, (see Phil. Mag. vol. xxxvii. p. 4.), this gas was observed to sound 52.95E+f+5 m above C. It must however Lie observed, that the results of the first and second sets of ex periments by these gentlemen, are most of them so greatly different, as to shew strongly the necessity of the repeti tions thereof that we have recommended above.
A very interesting memoir on the sounds produced by hydrogen gas, was published in the Journal de Physique, vol. lv. p. 165, by Dr Delarive of Geneva. Dr Higgins and Brugnatelli were the first who published an account of the sounds produced by hydrogen gas passing through a small tube. Professor Pictet made a series of experiments on these sounds, and describes the various musical phe nomena which are produced. He explained the influence on the sounds occasioned by the length or width of the tubes, and the situation were the hydrogen is burned ; but it was left to Dr Delarive to assign a very ingenious and plausible cause for the phenomena : He supposes, that a brisk vibratory motion is caused by the continual produc tion and condensation of aqueous vapour ; and that, in or der to produce a sound, this vibratory motion must be able to harmonise with the dimensions of the tube, and is then regulated and equalised by the regular reflections from the tube, so as to constitute together a clear musical sound. For this purpose there must be a great difference of tem perature in the air and the tube near the flame. For far ther information on this subject, see Nicholson's Journal, vol. i. p. 129, and vol. iv. p. 23 ; and Dr Thomas Young's A'atural Philosophy, vol. ii. p.