8 4 



NA TURE 



[A/ay 22, 1884 



of October there would be little or no chance of recovering the 

 comet. 



The comet's heliocentric equatorial-coordinates at perihelion 

 are — 



x ... -1-1148 r ... -o'43o5 z ... +o'ooi8. 

 If we combine these with the sun's coordinates, X. Y, Z, in 

 the Nautical Almanac, we readily obtain an idea as to the 

 chances of finding the comet, according to different assumed 

 dates of arrival at perihelion. The most advantageous condi- 

 tions are presented when this falls about the middle of April. If 

 we assume April 11, the R. A. is found to be 20S , N.P.D. 54°, 

 and the intensity of light 1 1 '05, which is four times greater than 

 on the date of the comet's discovery by Tuttle in 1858. As it 

 was then extremely faint, its rediscovery may be a matter of 

 difficulty. We have already one " Tuttle's comet," of short 

 period, and it may perhaps occur to astronomers that the third of 

 1858 will be aptly named Schulhof's cornel. 



CHEMICAL NOTES 

 Potilitzin has recently (Ber., xvii. 276) made some interest- 

 ing-observations on the hydration and dehydration of cobalt 

 chloride. He shows that, besides the already known hydraj^ 

 CoCU.6H 2 0, there exist two hydrates, CoCl„.2H 2 aid 

 CoCl 2 . H„0, the former being rose-red in colour, and the lat* 

 dark violet. When the dehydrated salt is heated to about 100". 

 it parts with water, which is again absorbed on cooling. When 

 an aqueous solution of the ordinary hexhydrated salt is heated, 

 or is mixed with a dehydrating agent, the colour changes from 

 pink to blue or dark violet. Potilitzin shows that this change, 

 which he proves to be due to partial decomposition of the hex- 

 hydrated salt, may be brought about without raising temperature 

 by the capillary action of unsized paper or a porous plate of 

 stucco. 



Tollens has made experiments on the sugar-like substance 

 obtained by the action of alkalies on an aqueous solution of 

 formaldehyde. Me oxidises methylic alcohol by air in presence 

 of platinum foil at 54°-55°, and distils ; he then treats the 

 crude distillate with baryta water, and so obtains a yellowish 

 precipitate, which, when freed from barium, yields an amorphous 

 syrup that reduces Fehling's solution, and gives results on 

 analysis approximating to the formula C 8 H )0 O, 5 . This syrup is 

 optically inactive, and does not undergo fermentation ; on treat- 

 ment with sulphuric acid, it gives formic and lactic acids 

 (Latuho. Versuchs-Stai., xxix. 355). 



Kannonikoyv (Bit:, xvii. p. 157, abstracts) attempts to 

 measure the refraction-equivalents of various metals by deducting 

 the refraction-equivalents of salts of these metals with organic 

 acids (determined with aqueous solutions of the salts) from the 

 refraction-equivalents of the acids themselves. So far as Ins 

 results go, they appear to indicate that the refraction-equivalents 

 vary periodically with variations in the atomic weights of the 

 metals. 



MM. Nilson and Petterson have prepared pure beryllium 

 chloride by heating the metal in perfectly dry hydrochloric and 

 gas, and have determined the density of the vapour of this com- 

 pound. Beryllium chloride can be volatilised without decom- 

 position in an atmosphere of dry nitrogen or carbon dioxide, 

 provided every trace of air is excluded. The density of the 

 gaseous compound for the temperature-interval 6S6°-8l2° agrees 

 with that calculated from the formula BeCU (Be = 9'l). The 

 question as to the value to be assigned to the atomic weight of 

 beryllium, which has been so much discussed of late, appears to 

 be now finally settled in favour of the number deduced by apply- 

 ing the periodic law to the study of the properties of this metal 

 and its compounds [ficr. xvii. 987). 



Continuing the researches of Kramers, Prof. Mendeleeff has 

 shown at a recent meeting of the Russian Chemical Society 

 ( Journal of the Society, vol. xvi. fasc. 2) that the densities of 

 solutions of salts increase together with the increase of their 

 molecular weights. Thus if we take the series of salts IIC1, 

 LiCl, NaCl, KC1, . . . BaCl„, SnCl 4 , HgCl,, and Fe 2 Cl„, the 

 molecular weights of which are respectively 36'5, 42 - 5, 5S'5, 

 74'5, . . . 208, 259, 271, and 325, the densities of their solu- 

 tions in 100 parts of water, at 15" to 20°, are: I "OIO, I '014. 

 I'023, I'025. . . . 1 -09s, I'io6, 1 -I2.S (calculated), and I'I34. 

 The densities increase as the molecular weights increase; but if 

 we take, instead of the molecular weights, the weights of their 



equivalents, or those of the equivalents of metals, the regularity 

 of increase disappears. Prof. Mendeleeff adds that the abovi 

 true, not only with regard to chlorides, but also with regard to 

 the salts of bromine and iodine, and many others. Reserving to 

 himself further to pursue his researches in this way, Prof. 

 Mendeleeff points out the following relation: — If the molecular 

 weight of the dissolved body be A/, and the solution be repre- 

 sented by n Al + iooIIjjO (where « represents the number of 

 molecules), the density, D, of the solution may be expressed foi 



many bodies by the following equation : — | — — | =A + Bn, 



\L> - dJ 



where D„ is the density of water, and k is equal to unity, or very 

 near to it. This equation must be considered, however, only as 

 preliminary, ulterior researches promising to give a more general 

 formula. A and B are two constants, which vary with the 

 temperatu -a. Thus, for HC1 at o° (the density of water at 4" 

 being taken =.1), A = 94-5 and B = 1725 ; at 20°, A = I02"2, 

 and B — i"8o ; at 40 A = io6'2, and B — I '85 ; at 60° A = 

 I05'2, and B = 2x15 ; at 8o° A — 1006, and B = 2^25 ; and at 

 ioo° A = 94-5, and B - 2'55, the coefficient k being in all cases 

 equal to unity. 



ON THE NOMENCLATURE, ORIGIN, AND DIS- 

 TRIBUTION OF DEEP-SEA. DEPOSITS 1 

 Introduction 

 *T I IK sea is unquestionably the most powerful dynamic agent 

 on the surface of the globe, and its effects are deeply im- 

 printed on the external crust of our planet ; but among the 

 sedimentary deposits which are attributed to its action, and among 

 the effects which it has wrought on the surface features of the 

 earth, the attention of geologists has, till within quite recent times, 

 been principally directed to the phenomena which take place in 

 the immediate vicinity of the land. It is incontestable that the 

 action of the sea along coasts and in shallow water has played the 

 largest part in the formation and accumulation of those marine 

 sediments which, so far as we can observe, form the principal 

 strata of the solid crust of the globe ; and it has been from an 

 attentive study of the phenomena which take place along the 

 shores of modern seas that we have been able to reconstruct in 

 some degree the conditions under which the marine deposits of 

 ancient times were laid down. 



Attention has been paid only in a very limited degree to de- 

 posits of the same order, and, for the greater part, of the same 

 origin, which differ from the sands and gravels of the shores and 

 shallow waters only by a lesser size of the grains, and by the fact 

 that they are laid down at a greater distance from the land and 

 in deeper water. And still less attention has been paid to those 

 true deep-sea deposits which are only known through systematic 

 submarine investigations. One might well ask what deposits 

 are now taking place, or have in past ages taken place, at the 

 bottom of the great oceans at points far removed from land, and 

 in regions where the erosive and transporting action of water has 

 little or no influence. Without denying that the action of the 

 tidal waves can, under certain special conditions, exert an erosive 

 and transporting power at great depths in the ocean, especially 

 on submerged peaks and barriers, it is none the less certain that 

 these are exceptional cases, and that the action of waves is almost 

 exclusively confined to the coasts of emerged land. There are 

 in the Pacific immense stretches of thousands of miles where we 

 do not encounter any land, and in the Atlantic we have similar 

 conditions. What takes place in these vast regions where the 

 waves exercise no mechanical action on any solid object ? We are 

 about to answer this question by reference to the facts which an 

 examination of deep-sea sediments has furnished. 



A study of the sediments recently collected in the deep sea 

 shows that their nature and mode of formation, as well as their 

 geographical and balhymetrical distribution, permit deductions 

 to be made which have a great and increasing importance from - 

 geological point of view. In making known the composition o 

 these deposits and their distribution, the first outlines of a geo- 

 logical map of the bottom of the ocean will be sketched. 



I his is not the place to give a detailed history of the various 

 contributions to our knowledge of the terrigenous deposits in deep 

 water near land, or of those true deep-sea deposits far removed 

 from land, which may be said to form the special subject of thi 

 communication. From the time of the first expeditions under 

 1 A Paper read liffcre the Royal Society of Edinburgh by John Murray 

 and A. Renard. C< mmrnicaiea by John Murray. 



