374 



NATURE 



[Feb. 17, 1 88 1 



Eerthelot has recently succeeded in isolating several com- 

 pounds of metallic chlorides with hydrochloric acid ; in Compt. 

 rend, he describes three such chlorliydrates of metallic chlorides, 

 viz. : — 



CdCl2.2HCl.7H2O; Pblj.HI.sH.O; and3AgI.HI.7H2O; 

 and in another number of the same journal M. Ditte describes, 

 among others, the salts BiCla . 3HCI ; SbClj. 3HCI, &c. These 

 hydrated salts are formed from their constituent compounds with 

 a considerable evolution of heat, the amount varying from 

 11,000 to 15,000 units. The anhydrous salts readily undergo 

 dissociation into their constituent compounds, and cannot there- 

 fore be readily obtained. Berthelot regards the formation and 

 dissociation of these chlorhydrates as playing an important part 

 in the mechanbm of many chemical changes. Thus calomel is 

 changed into corro»ine .■■ublimate and mercury by the action of 

 hydrochloric acid : Berthelot would formulate this change as 

 HgjCla + xHCl = HgCl, . .iHCl + Hg (attended with evolu- 

 tion of 9500 heat-units), with subsequent dissociation of the 

 chlorhydrate of HgCU. Again in the reduction of metallic 

 chlorides by hydrogen Berthelot supposes that chlorhydrates are 

 produced, and that the heat thus developed aids in dissociating 

 fresh quantities of the original metallic chloride ; thus he would 

 indicate the initial stage of the reduction of cadmium chloride 

 by hydrogen, as : — 



aCdClj + n, =CA + CdClj . 2HCI. 

 M. WuRTZ has recently been studying {Compt, rend.) the 

 action of the ferment Papain on fibrin, whereby the fibrin is 

 rendered soluble in water. The process appears to he analogous 

 with many ordinary chemical changes in which the formation 

 and decomposition of a compound are continually proceeding. 

 Papain forms an insoluble compound with fibrin, which com- 

 pound is then decomposed by the water present with formation 

 of a soluble hydrated fibrin, and setting free of the ferment, 

 which again acts on fresh quantities of fibrin. 



In the American Chem. fourn. Clarke and Stallo describe a 

 series of experiments on the tartrates of antimony, wherein they 

 are led to regard tartar emetic as the potassium salt of a new 

 acid, to which they give the name iartratitimonioiis, viz. 

 Sb . C4H4O6 . OH. This acid they regard as derived from 

 orthantimonious acid, Sb{0H)3, which they have prepared in 

 definite form. The behaviour of an aqueous solution of tar 

 trantimonious acid towards heat is peculiar. Below 30° the solu- 

 tion remains nearly clear ; at a few degrees above 30° a white 

 curdy precipitate deposits ; on evaporating in a water bath the 

 ciu"dy precipitate disappears and a transparent gummy mass 

 remains, which is completely soluble in cold water, re-forming 

 the original acid. These clianges are shown to be expressible 

 by the equations — 



1. C4H5Sb07 -H 2H„0 =: SbHjOa -1- C^HsOg ; the curdy pre- 

 cipitate consisting of orthantimonious acid. 



2. CjHgOg + SbHjOs - 2H„0 -I- CjHsSbO^; i.e. on heating, 

 water is eliminated, and the original acid is reproduced. 



In a series of papers in the Berliner Berichte Th. Thomsen 

 endeavours to show that the "molecular rotation" of many 

 classes of compounds is, for each class, a simple multiple of a 

 constant number. " Molecular rotation " he defines as rotatory 



,, molecular weight /M-ioJo 



power X ^— 1 =- 



100 \ 100 



The constant for one 



group appears generally to bear a simple relation to that for 

 other groups ; in fact a constant may be found which belongs to 

 many groups. Adopting a classification analogous to that of 

 natural .history, Thomsen shows that the constant o'95 belongs 

 to a large "class" of compounds; that this multiplied by 4 

 gives the constant (3'S) for the "family" of alcohols, and by 

 9 gives the constant (8"65) for the "family" of amides, &c. 

 From a determination of the molecular rotation of compounds, 

 aided by the use of these constants, he attempts also to deduce 

 conclusions as to the chemical structure of the molecules of 

 these compounds. 



In various papers noticed in this journal, Briihl attempted to 

 show that the " molecular refraction " j M.(^i-^J I of isome- 

 ric carbon compounds is constant when only " singly-linked " 

 carbon atoms are present ; and that variations in this quantity 

 are to be traced to variations in the " linking" of carbon atoms. 

 Janowsky (Berliner Berichte) maintains that slight differences 



are always noticeable between the molecular refractions of iso- 

 meric compound where isomerism is due not to "linking," but 

 to "grouping" of carbon atoms: but he thinks that if the 

 values of the refractive indices of such compounds are con- 

 sidered, better results are obtained than by calculating the mole- 

 cular refractions. Briihl houever had himself shown that the 

 refraction indices of such isomers are not the same. 



Landolt has gathered together in Berliner Berichte the more 

 important data concerning the inversion of specific rotatory 

 power of carbon compounds by the influence of heat or of 

 inactive solvents : those data he supplements by further experi- 

 ments of his own, and develops shortly the outlines of a mecha- 

 nical theory analogous to that of Rammelsberg. 



The atomic weight of beryllium is still the subject of experi- 

 ment. Emer5on Reynolds has redetermined the specific heat of 

 the pure metal (Cluin. A'e7vs) and obtained a number which 

 points to 9'i as the true atomic w-eight. The same value is 

 assigned by Brauner, who (Berliner Berichte) criticises the 

 arguments of Nilson and Petter^son, and attempts to show that 

 the specific heat, specific volume, and general physical properties 

 of beryllium oxide are more in keeping « ith the formula BeO 

 (Be = 9'i) than with the formula iie.^O^ (Be = I3'6) assigned 

 to it by the Swedish observers. 



In a paper on bismuth compounds in Chem. Soc. Journal, by 

 Muir, Hoffmeister, and Robbs, the new salts bismuth fluoride 

 (BiFj) and bismuth oxyfluoride (BiOF) are described. The 

 former is the more stable of the halogen compounds of bismuth : 

 it is not decomposed by water, and is scarcely changed at a red 

 heat in air. 



Prof. Beilstein, who has recently studied the various sub- 

 stances used for disinfection, arrives, in a communication made 

 to the St. Petersburg Technical Society, at the following con- 

 clusions: — Sulphuric acid would be the best di iufectant if it 

 did not de-troy the sides of the tanks ; the use of lime and of 

 salts of lime ought to be completely renounced, as they but tem- 

 porarily destroy bacteria, and under some circumstances may 

 contribute to their development ; nor does sulphate of iron, even 

 in a solution of 15 per cent., ultimately destroy bacteria, as they 

 revive when | ut into a convenient medmm. Therefore Prof. 

 Beilstein recommends sulphate of aluminium, which is used in 

 paper and priuted-cotton manufactures. The best means for 

 providing it is to make a mixture of red clay with 4 per cent, 

 of sulphuric acid, and to add to this mixture some carbolic acid 

 for destroying the smell of the matter which is to be disinfected. 



ACTION OF AN INTERMITTENT BEAM OF 

 RADIANT HE A T UPON GASEOUS MA TTER ' 

 "T^HE Royal Society has already done me the honour of 

 publishing a long series of memoirs on the interaction of 

 radiant heat and gaseous matter. These memoirs did not escape 

 criticism. Distinguished men, among whom the late Prof. 

 Magnus and the late Prof. Buflfmay be more specially mentioned, 

 examined my experiments, and arrived at re-ults different from 

 mine. Living workers of merit have also taken up the question, 

 the latest of whom,'' while justly recognising the extreme difficulty 

 of the subject, and while verifying, so far as their experiments 

 reach, what I had jjublished regarding dry gases, find me to 

 have fallen into what they consider grave errors in my treatment 

 of vapours. 



None of these investigators appear to me to have realised the 

 true strength of my position in its relation to the objects I had in 

 view. Occupied fa the most part with details, they have failed 

 to recognise the stringency of my work as a whole, and have not 

 taken into account the independent support rendered by the 

 various parts of the investigation to each other. They thus ignore 

 verifications, both general and special, which are to me of con- 

 clusive force. Nevertheless, thinking it due to them and me to 

 submit the questions at issue to a fresh examination, I resumed 

 some time ago the threads of the inquiry. The results shall in 

 due time be communicated to the Royal Society ; but mean- 

 while I would ask permission to bring to the notice of the 

 Fellows a novel mode of testing the relations of radiant heat to 

 gaseous matter, whereby singularly instructive effects have been 

 obtained. 



After working for some time with the thermopile and galvano- 



^ Paper read at the Royal Society, January 13, by Prof. TyndalJ, F.R.S 

 '' Lecher and Pernter. Philosofhical Magazine. January, 1881 ; Sitzh. der 

 ft. Akad. der Wissenscll. in tVien, July, 1880. 



