November 2, 1893] 



NA TURE 



this connection, viz. that in Saukaravijaya of Vidyaranya, the 

 same positions are given for the planets at the birth of Saukara- 

 chrirya, with the exception of the Moon, which is in Arthra, i.e. 

 Gemini, 6" 40' to 20° o' of the Hindu zodiac. These positions of 

 the Sun, Moon, Jupiter, and Saturn took place on the 1st of 

 Mcsham, Kali Yuga 4221, corresponding to March 30, A.D. 

 1 1 19, without change of the present style, 



I am afraid, however, that these dates will hardly suit my 

 Hindu friends, whose devotion to these great personages gives 

 them a sense of "distance" which is best satisfied when ex- 

 pressed in years ! I give these notes, however, for what they 

 may be worth. 



Adyar, Madras. Walter R. Old. 



Note. — According to the Suryasiddhanta rules for com- 

 puting the longitudes of the planets, I find thct Mars was in 

 Capricorn, its "exaltation" Sign, in the month o( Mesha/n, 

 K.Y. 1341, as required by the data given for Rama's epoch, 

 its longitude in the Hindu zodiac being Capricornus 13°. — 

 W. R. O. 



On the Latent Heat of Steam. 



Since the invention of M. Berthelot's extremely elegant and 

 simple apparatus, described in his " Mecanique Chimique," 

 vol. i. p. 28S, the approximate determination of the latent heat 

 of vaporisation of liquids has become comparatively easy. The 

 exact evaluation of the correction due to the heating of the 

 calorimeter from extraneous sources is, however, a matter of 

 considerable difficulty with the original form of apparatus. 

 The correction is necessarily calculated from data supplied by 

 the thermometric observations made previously to, and after, 

 the actual condensation of the liquid has taken place. For this 

 calculation to be as simple and satisfactory as possible, it is 

 essential that during the whole experiment the temperature of 

 the bodies in the immediate neighbourhood of the calorimeter 

 shall remain approximately constant. In M. Berthelot's method 

 of determination this condition is however not strictly fulfilled. 

 Forduring the "preliminary period-,'' although theflameis lighted 

 over the calorimeter, the liquid in the flask has not yet begun to 

 boil, so that the radiation to the calorimeter varies, and during 

 the "final period" the flame is extinguished and no lurther 

 heat reaches the calorimeter from this source. Also during 

 the beginning of the " middle period," a considerable 

 amount of liquid which has been volatilised from the flask at a 

 temperature below its boiling-point, reaches the worm and 

 is there condensed. We therefore modified the apparatus 

 in such a way that the flame was at a constant height and the 

 liquid was boiling duriii^^ the ivhole time of the experiment, in- 

 cluding both the preliminary and final periods. We found 

 that under these circumstances, with a rise of 3^ or 4° in ten 

 minutes, the Regnault-Pfaundler correction is perfectly accurate. 

 We propose shortly to publish a complete description of our 

 apparatus, and shall not therefore go into details at present. It 

 differs mainly from that of M. Berthelot, by the insertion in the 

 interior of the boiling flask of a glass valve, which is opened 

 when the rise of the thermometer in the calorimeter has become 

 steady, and closed when sufficient liquid has been condensed in 

 the worm. The vapour during both the preliminary and final 

 periods passes into a reversed condenser. 



Our main reason for this communication is to record the 

 somewhat remarkable results obtained with water, and to ask if 

 any of your readers can give information as to any accurate 

 work upon the latent heat of steam published since that of 

 Regnault {Memoires de V Acadi-mie des Sciences, t. 21) in 1847. 



We give the results of five experiments (done at pressures 

 differing but little from 760 mm.), which are still subject to cer- 

 tain corrections not exceeding ± i unit. 



Latent 

 heat of 

 steam (L\ 

 525-6 

 5247 

 5266 

 525-0 

 523-9 



It will be noticed that in experiment 5, where the amount of 

 water condensed was purposely reduced, so as to increase as far 

 as possible the experimental error, the result obtained differs but 

 slightly [from the mean. This mean, 525-2 (omitting experi- 



NO. 1253, VOL. 49] 



\Vt. of water Time of Rise of temp, 

 condensed condensation in calorimeter 



T 

 L =i(S 



ment 5, 525 5) is over 2 per cent, lower than that of Regnault. 

 The thermometer used was one divided into fiftieths of a degree, 

 by Baudin, and was compared with a thermometer calibrated at 

 the International Bureau of Weights and Measures. Every 

 precaution was taken to ensure accuracy of reading. 



We have sought for confirmation of our results in the indirect 

 determinations of other observers. If we insert the latest values 

 for the specific volume of steam at 99 6 given by Perot {Ann. 

 Chim. et Phys. [6] 13, p. 159) and for the mechanical equivalent 

 of heat by Griffiths ' (Nature, vol. xlvii. p. 476) in the ther- 

 modynamic formula, 



J dt 



we find the number 52743 for the value of L at 99-60' C.- 

 The number given by Regnault for lOo' C. is 536-7. We 

 have also selected from the numerous results obtained 

 by Joly {Proc. Per. Soc. vol. xli. p. 358) with his steam 

 calorimeter those relating to silver, which is a substance easy 

 to obtain in a state of purity. If we take the number given 

 by Regnault for the specific heat of silver, we find his own 

 determination of the latent heat of steam confirmed. On the 

 other hand the concordant numbers for the specific heat of silver, 

 given independently by Koppand Bunsen, lead to a result about 

 I A per cent, lower than that of Regnault. 



The complete discussion of such results, however, is a matter 

 of great difficulty owing to the uncertainty w^hich prevails with 

 regard to the specific heat of water. We have not as yet suc- 

 ceeded in discovering any constant error capable of explaining 

 the discrepancy between our result and that of Regnault, but 

 further experiments are now in progress. 



The question, as need hardly be pointed out, is of consider- 

 able practical importance in connection with problems relating 

 to the steam engine. P. J. Hartog. 



J. A. Harker. 



Physical Laboratory, Owens College, October 19. 



Artificial Amcebse and Protoplasm. 



Ln No. 1 25 1 of Nature, Dr. John Berry Haycraft has written 

 a review on Prof. O. Biitsc hii's investigations of microscopic 

 foams and protoplasm. 



The biological parts of the contribution I may leave my 

 colleague, Prof. Butschli, to answer, but as my investigations 

 are also mentioned, and my name several times quoted, though 

 always mis-spelled as " Nuincke," instead of Quincke, I may 

 perhaps be allowed to call attention to the fact that 1, 

 not Prof. Butschli, as the reviewer asserts, was the first who 

 tried to explain the movements of amoebse and protoplasm by 

 physical laws, by the periodical spreading of a soap solution. 

 In 1879 I explained the voluntary formation of an emulsion ob- 

 served by Prof. Gad, and the amceboid movements of oil- 

 drops by the periodical spreading of a soap solution upon 

 the common surface of oil and water, and I said "that 

 foam is an emulsion of air instead of oil, and that the durability 

 of foam depended on the same conditions as the durability of 

 an oil emulsion." -^ In a continuation of these investigations I 

 explained in the year iSSSthe movements of protoplasm by the 

 same physical principles, making the supposition that it was 

 intermixed with thin oil-films, and in the cells of plants, sur- 

 rounded by an oil-coat. ^ I there fore believe I was the first to 

 point to the foamy structure of protoplasm, which was later on 

 further investigated by Prof. Butschli. 



Is Dr. John Berry Haycraft acquainted with my investiga- 

 tions, and from whence does he deduce the right of calling them 

 " toys for the physicist " ? They form the conclusion of a series 

 of researches on capillarity which I began 37 years ago, an d by 

 vvhich I, for the first time, showed that surface-tension is con- 

 siderably altered by layers of a foreign substance of far less 

 thickness than i/io of a light-wave ; for the first time, also, the 



1 We understand that Mr. Griffiths' number is still subject to a slight cor- 

 rection, but that this does n.,t amount to i part in 1000. 



- -£ was calculated from Roche's formula quoted by Hirn, Th^orie 



JMc'canique de la Chaleur, t. J. p. 325. 



-> G. Quincke, '' Ueber Emulsions bildung und den Einfluss der Galle auf 

 die VerdanuDg" (F/iii^er's .-irc/ik'. 1879, p. 144). 



■* G. Quincke." Ueber periodische Ausbreitung an Fliissigkeits oberflachen 

 und dadurch hervorgeru'ene Bewegungserschemungen " (Sitz/ingsber. dey 

 Bcrtiner Akad. 12, 7, 1SS8. \riedeiu. Aiui. 35, p. 580-642, 1S88). " Ueber 

 Protoplasma bewegungen und verwandte Krscheinungen " (^'d^f^/a// der 

 62 I'ersainmliiHg Deiitscher Naiur/orscher itnd Aerzie, Heidelberg, 1889, 

 p. 204-7). 



