5IO 



NATURE 



[March 29, 1894 



dibasic acids ; of Prof. Tail on impact ; of Mr. Aitken on the 

 particles in fogs and clouds ; of Dr. John Murray on the 

 chemical changes which take place in the composition of sea- 

 water associated with blue-muds on the ocean floor ; and of Dr. 

 Po!e on colour-blindness. Prof. Copeland's paper on Nova 

 Aurigffi is included ; and also that of Prof. Knott on circular 

 magnetisation ; of Prof. Ewart on the lateral sense-organs of 

 Elasmobranchs ; of Prof. James Geikie on the glacial succession 

 in Europe ; of Dr. Notl Paton on the action of the valves of 

 the mammalian heart ; and of Dr. Maclarlane on the minute 

 structure of plant hybrids in relation to that of their parents. 



Rather more than one hundred years ago Christian Konrad 

 Sprengel gave to the world his investigations on flower-fertili- 

 sation. The acute observations contained in " Das Entdeckte 

 Geheimniss der Natur im Bau and in der Befructung der 

 Blumen'" — the secrets of nature in the forms and fertilisation of 

 flowers discovered — have been reprinted by Engelmann, of 

 Leipzig, in Nos. 48-51 of Ostwald's Klassiker der Exakten 

 Wissenschaften. Every naturalist now knows that Sprengel's 

 theory of insect fertilisation was not a full interpretation of 

 nature's secrets. His careful observations, however, were of 

 prime importance in helping to establish the true theory of 

 cross-fertilisation presented by Darwin some seventy years after 

 the publication of his work. In addition to the above reprint 

 we have received No. 44 of the same series, entitled " Das 

 Ausdehnungsgesetz der Gase." The volume contains a capital 

 collection of papers on the law of gaseous expansion, by Gay- 

 Lussac, Dalton, Dulong and Petit, Rudberg, Gustav Magnus, 

 and Regnault, published from 1802 to 1842. 



There is a school of philosophers who insist that all in- 

 investigation into the causes of things is wasted labour, and that 

 science progresses solely through the study of phenomena and 

 their laws. Mr. Lester Ward is not one of these, for in a lecture 

 on the " Status of the Mind Problem," recently delivered before 

 the Anthropological Society of Washington, he showed that 

 the work of Ramon y Cajal, and others, indicated that proto- 

 plasm is not merely the physical basis of life, but is the physical 

 basis of mind also. In his words, "the prevailing fashion 

 among scientific men of emphasising the ' mystery of mind ' is 

 unnecessary and illogical, since mind is no more a mystery than 

 matter, and all that there is any ground for confessing is that, 

 in consequence of the greater complexity of mental phenomena, 

 due to the higher state of development of the material basis of 

 mind, we possess as yet much less knowledge of them than we 

 do of many of the simpler phenomena of nature." 



\\K SERIES of compounds of sugars with mercaptans, the 

 sulphur alcohols, of a nature similar in many respects to that of 

 the recently isolated glucosides formed by the combination of 

 ordinary alcohols with the sugars, are described by Prof. Emil 

 Fischer in the current Berichte. These new substances dift'er 

 from the glucosides of the alcohols in their constitution, how- 

 ever, for they contain two equivalents of the sulphur alcohol to 

 one equivalent of the sugar ; hence they are more nearly allied 

 to the similarly constituted compounds of mercaptans with 

 ordinary aldehydes. The members of the series fully described 

 are the ethyl mercaptals of grape sugar and of galactose, and 

 the amyl mercaptal of the former. In addition to these Prof 

 Fischer has isolated the ethyl mercaptals of mannose, arabinose, 

 rhamnose, and a-glucoheptose, and has qualitatively proved the 

 generality of the reaction for xylose, maltose, and milk sugar. 

 The compounds appear likely to prove of very great importance, 

 for their formation occurs so readily, that they will serve admir- 

 ably in many cases as valuable aids in the identification and 

 isolation of either the well-known or newly-discovered sugars. 

 The amyl compound in particular appears likely to be of great 

 service, on account of its slight solubility. They are all sub- 

 NO. 1274, VOL. 49I 



stances of considerable stability, and crystallise well. Glucose 

 ethyl mercaptal, CgHiaOjCSCoHg),, is prepared by mixing ethyl 

 mercaptan with an ice-cold solution of grape sugar in fuming 

 hydrochloric acid. Upon cooling, after the slight rise of tem- 

 perature which accompanies the reaction, crystals of the new 

 compound separate, and may be advantageously recrystallised 

 from absolute alcohol. The reaction is simply an addition of 

 two molecules of the mercaptan to one of glucose with elimina- 

 tion of a molecule of water. 



QHiaOg + 2C0H5SH = CeHi205(SC2H5)o + H.p. 

 Glucose ethyl mercaptal crystallises in colourless needles 

 and plates, which possess a taste very different to that of sugar, 

 being disagreeably bitter. The crystals melt at 127 , and the 

 liquid may be partially distilled at a higher temperature. The 

 substance is only slightly soluble in cold water, and the solution 

 is Isvo-rotatory. It behaves as a weak acid, and it is some- 

 what remarkable that alkalies dissolve the crystals in large 

 quantity, and upon the addition of a dilute acid the compound 

 is precipitated. Indeed the sodium salt, CjoHjiS^OjNa, has 

 been isolated in well-defined crystals by treating the compound 

 with sodium dissolved in methyl alcohol. That the substance 

 is very different in its nature from the original glucose is further 

 evidenced by the fact that it does not reduce Fehling's solution. 

 The other members of the series appear to be characterised by 

 similar but graduated properties, the solubility, for instance, 

 diminishing as the homologous series of mercaptans is ascended. 



Chloraurate of silver, AgAuCl4, an interesting compound of 

 the very soluble and deliquescent chloride of gold with the 

 particularly insoluble chloride of silver, is described by Dr. 

 Hermann, of Aschaffenburg, in the same number of the Berichte. 

 This compound has formed the object of previous unsuccessful 

 researches, but its preparation is very simple when the neces- 

 sary conditions are known. Four parts by weight of metallic 

 gold is dissolved in aqua regia, and the solution evaporated 

 over the water bath, until upon cooling the resulting chlorauric 

 acid, HAUCI4, crystallises. One part by weight of stiver dis- 

 solved in dilute nitric acid is then added, when silver chloride 

 is precipitated in its usual form. Upon repeated evaporation 

 of the whole with concentrated nitric acid containing a trace of 

 hydrochloric acid the silver chloride changes, becoming coloured 

 bright red, and eventually is completely converted into a mass 

 of crystals of silver chloraurate. The crystals are long prisms 

 terminated by pyramids and dome-faces ; they appear to be 

 coloured bright orange-red when singly examined by reflected 

 light, but are pure yellow by transmitted light, and the 

 finely-powdered substance reflects bright yellow light. It 

 is interesting to note that when enclosed in a sealed tube con- 

 taining perfectly dry air the compound is quite stable and un- 

 affected by bright sunlight, but the moment it is exposed to 

 sunshine in ordinary moist air it commences to bronze, and 

 eventually becomes superficially coated with a dark bronze 

 metallic coating. Dilute hydrochloric acid instantly decomposes 

 it with formation of silver chloride and a solution of chlorauric 

 acid. Ammonia, on the other hand, decomposes it with pro- 

 duction of the usual ammoniacal solution of silver chloride and 

 deposition of fulminating gold. 



The additions to the Zoological Society's Gardens during the 

 past week include a Vervet Monkey {Cercopitheais lalandii) 

 from South Africa, presented by Mrs. White ; two Cockateels 

 [Calopsitta novts- holla ndice) from Australia, presented by Mrs. 

 Tidey ; a Leadbeater's Cockatoo (Cacatua leadbcateri) from 

 Australia, presented by Mr. J. Ward ; a White-bellied Eagle 

 {Haliaetus leucogaster) from Australia, presented by Mrs. 

 Scales ; a Ring-necked Parrakeet {Palaornis torquatiis) from 

 India, presented by Miss Castle ; two Peregrine Falcons {Falco 

 peregrinus) British, presented by Mr. Penn C. Sherbrooke ; a 



