December 7, 1893] 



NA TURE 



^39 



combination invariably renders it again moist before explosion 

 occurs. 



It has been currently supposed that I he presence of sharp solid 

 fragments, such as those of glass, exerts a lowering effect upon 

 the temperature of explosion of hydrogen and oxygen. This 

 supposition has been practically tested and found wanting in 

 accuracy. Neither glass fragments nor sea-sand were found to 

 reduce the temperature below the limits abovestated. A remark- 

 able result, however, was obtained when pieces of platinum foil 

 and wire were introduced into the explosion bulb. It was found 

 impossible in their presence to bring about an explosion, even 

 when the temperature of the bath was raised to 715°. Quiet 

 combination invaiiably ensued. 



The size of the explosion vessel appears to be immaterial, 

 except when reduced to very small dimensions, such as 4'5 mm. 

 diameter, as in the case of the smallest bulb tested, when the 

 range of molecular forces is approached. In six experiments 

 with this small bulb no explosion occurred ; in others the 

 explosion did not occur in the vessel, but the quiet combustion 

 there initiated was transmitted along the leading tube, through 

 the tube containing the brass gauze discs, and eventually 

 occasiored an explosion in the wash-bottle, disastrous to the 

 latter. 



In the cases of other explosive mixtures the admixture was 

 effected, in the proper proportion, in a three litre flask, from 

 which the gases were driven first through a wash-bottle, and 

 subsequently through a test-tube, arranged likewise as a small 

 safety wash-bottle, to prevent the explosion reaching the larger 

 one. 



Carbon monoxide and oxygen, in the proportion to form 

 carbon dioxide, were found to suffer, for the most part, silent 

 combination in the apparatus, and the wide limits of the observed 

 temperatures of explosion, 636" to 814°, in those cases when 

 explosion did ensue, were found to be due to more or less of 

 such silent combination. 



Gaseous mixtures of hydrocarbons and oxygen were found, 

 however, with the exception perhaps of marsh gas and oxygen, 

 to exhibit practically no quiet combination ; and these mixtures 

 have afforded most trustworthy and constant temperatures of 

 explosion. 



Mar.-h gas was found to explode, as a rule, with oxygen at 

 temperatures varying from 656° to 678^, but occasionally quiet 

 and complete combustion occurred. Other hydrocarbons never 

 failed to yield an explosion. 



Ethane detonated with oxygen in three experiments at 622', 

 605°, and 622° respectively. A mixture of ethylene and oxygen 

 exploded at 577°, 590°, and 577^ in three consecutive experi- 

 ments. Acetylene prepared by Gatiermann's method, which 

 in Prof. Meyer's experience yields it in a purer state than the 

 more recent convenient method discovered by Maquenne, ex- 

 plodes with oxygen with exceptional violence, the wash-bottle 

 being destroyed in every experiment. The temperature of this 

 explosion was very constant, 510°, 515°, and 509" being suc- 

 cessively observed. Propane mixed with five times its volume 

 of oxygen likewise exhibits a very constant temperature of 

 ignition, 548°, 545°, and 548° being indicated in three deter- 

 minations. Propylene exploded with four and a half times its 

 volume of oxygen at 497°, 511°, and 499°. Isobufane mixed 

 with six and a half times its volume of oxygen detonated at 

 549°, 550°, and 545° ; and isobutylene at 546°, 548°, and 537'. 

 Finally, coal gas mixed with thrice its volume of oxygen was 

 found to explode in three experiments at the remarkably con- 

 stant temperatures of 649", 647°, and 647°. It was found im- 

 possible, however, to induce a mixture of coal gas and air to 

 explode under these experimental conditions. 



It will be clearly seen from the above experiments with 

 gaseous mixtures of hydrocarbon and oxygen, that the tempera- 

 ture of explosion falls as the content of carbon increases. Thus 

 the mean temperatures for methane, ethane and propane are 

 667°, 616", and 547' respectively. Further, the temperature 

 also falls with the degree of saturation, or in other words, the 

 less saturated the hydrocarbons become the more readily do they 

 ignite in contact with oxygen. Thus ethane, ethylene and 

 acetylene explode wi!h oxygen at 616^, 580' and 511°; 

 propane and propylene at 547° and 504° ; and isobutane and 

 isobutylene at 548° and 543°. It will also be observed, liowever, 

 as would be expected, that these differences due to difference 

 of saturation diminish as the series are ascended. 



A, E. TUTTON. 



NO. T258, VOL. 49] 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge. — Mr. Austen Leigh, Provost of King's, the 

 Vice-Chancellor, has been appointed a member of the Geo- 

 graphical Committee, in the place of Dr. Ferrers, resigned. 

 The award of the Geographical Studentship of ^loo will be 

 made towards the end of the Lent Term. 



The first award of the Walsingham Medal, founded by the 

 Lord High Steward for the encouragement of biological research, 

 has been made to Mr. E. W. MacBride, Fellow of St. John's, 

 for his monographs in zoology. 



Mr. Arthur Wilt.ey, at present giving a course of lectures 

 in Columbia College, New York, has been elected to the vacant 

 Balfour Studentship by the Special Board of Biological and 

 Geological Studies of the University of Cambridge. It is under- 

 stood that the investigation prescribed for him will be that of the 

 embryology of Nautilus poinpilius, for which purpose he will 

 proceed to the South Seas. 



SCIENTIFIC SERIALS. 



The Quarterly yoiirnal of Microscopical Science for September, 

 1893, contains studies on the comparative anatomy of sponges : 

 V. Observations on the structure and classification of the Cal- 

 carea Heterocccla, by Dr. Arthur Dendy (plates IO-14). In 

 this paper the author gives a general account of the anatomy, 

 histology, and classification of the Calcarea Heterocwla, from the 

 point of view of one who has for a long time past been engaged in 

 an independent study of the group, and he brings together all that 

 is known on the subject. While on the classification of the group 

 he departs somewhat widely from the lines laid down by pre- 

 vious writers, yet the necessity of doing so was forced upon him 

 by a study of nearly fifty Australian species. The author finds 

 neither the canal system nor the skeleton affords a reliable guide 

 for classification, and a compromise is the only satisfactory way 

 out of the difficulty. The families adopted are : (i) Leucasidse, 

 (2) Sycettidse, (3) Grantid?e, (4) Heteropidte, (5) Amphoriscidae. 

 — On some points in the origin of the reproductive elements in 

 Apus and Branchipus, by J. E. S. Moore (plates 15 and 16). 

 Calls attention to some important details in the spermatoge- 

 nesis of Branchipus and in the ovigenesis in Apus. In the former, 

 the observations bear out the general law as to the similarity of 

 the male and female cells, their specific peculiarities being ])hy- 

 siological in origin, without morphological import. The divi- 

 sional phenomena of these cells are intimately related to a 

 protoplasmic structure, which might be fitly described as 

 " Schaumplasma," and one of the initial impulses towards 

 metamorphosis is a fusion of some of the intra-nuclear globules ; 

 while a considerable portion of the complicated karyokinetic 

 figures, with their centrosomes, pseudosomes, and dictyosomes, 

 appear to be the logical as well as the actual consequence of the 

 continuance of this process. Some time before and always 

 during the course of the chromatic changes bodies answering to 

 the centrosomes in all details except in their numbers, which is 

 much greater, make their appearance ; these the author provi- 

 sionally names " pseudosomes." The term "dictyosomes" is 

 given to bodies which make their appearance connected one to 

 another and to the inner group of chromosomes by fine strands, 

 and which remain uncoloured by reagents, and are more or less 

 related to the cell periphery. (In connection with these, Farmer's 

 notes and figures of like bodies in the Pollen mother-cells is of 

 interest. (See Ann. of Bot. September, 1893).— Notes on the 

 Peripatus of Dominica, by E. C. Pollard (plate 17). Miss 

 Pollard's species is apparently very nearly related to P. echvardsii, 

 but differs in the number of ambulatory appendages, there being 

 29 to 34 pairs in P. edwardsii, while in P. dominicir, sp. nov. , 

 there are from 25 to 30. — Studies on the Protochordata, by 

 Arthur Wiley, B.Sc. (plaies 18-20). II. The development of 

 the neuro-hypophysial system in Ciona intestinalis and Clave- 

 Una lepadijormis, with an account of the origin of the sense- 

 organs in Ascidia meiitula. III. On the position of the mouth 

 in the larvae of the Ascidians and Amphioxus, and its rela- 

 tions to the Neuroporus. 



Symons's Monthly Meteorological Magazine, November. 

 Mr. Symons gives a summary of all the rainfall observations 

 known to have been taken in Persia ; the only places at which 

 such appear to have been made are Ooromiah, in the north- 



