90 



NA TURE 



[NoVEMBEk 28, 1 901 



Preliminary IxvKSTir.ATiON oi- the Diameter of 

 Mars. — I'rof. T. J. J. Sec, in continuation of his work on 

 planetary diameters, gives the results of old and new measures 

 of the disc of the planet Mars in Aslrouomisilu NathrichUn, 

 lid. 157, No. 3750. The measures published from 1651-1901 

 are tabulated and divided into two categories, according to their 

 being determined with the wire micrometer or the heliometer. 

 The values obtained in these two ways are markedly different, 

 the mean diameter from the wire micrometer being 9'67S, that 

 from the heliometer 9'338, at mean distance. This discrepancy 

 has been usually attributed to irradiation. A considerable 

 number of experimental trials have been made at the Washing- 

 ton Observatory in order to get a trustworthy value for the correc- 

 tion due to this cause, and the results obtained from a recent 

 series of determinations, using liquid screens in the eyepiece, are 

 given. The polar diameter of the planet is thus estimated as 



9"'222 + o"'OI3 

 = 6687 km. ± 10 km. 

 Assuming an oblateness of i in 200, the equatorial diameter 

 may be taken as = 9""30 = 6743 km. 



Dehnitive Orbit Elements of Comet 1899 I. — Mr. 

 C. J. Merfield, of Sydney, has computed the definitive elements 

 of the orbit of this comet from the available observations during 

 the period 1899 March 4-August 10. 



EUments. 

 Epoch of osculation 1S99 March 12. 

 T = 1899 April 12-978010 G.M.T. 



0) = 8 4r 46'48] 



& = 24 59 5993 [1900-0 



i= 146 15 30'29J 

 log q = 9'5'39795 

 log e = 0-0001521 



e = I -00035029. 



In the course of the article many hitherto isolated descriptions 

 of the varying appearances of the comet during its period of 

 visibility are brought together. Throughout March 1899 the 

 comet appeared as a nebulous mass 4' or 5' of arc in diameter, 

 with a central condensation. After perihelion passage many 

 changes commenced to be presented. Prof. Perrine, at Lick, 

 observed the nucleus to be double, and obtained measures of 

 the components, the distance between them increasing from 

 l2"-lS" of arc during the period 1899 May 11-14. This 

 feature was later confirmed by Prof. Barnard, who measured the 

 two nuclei with the Yerkes refractor, and found the separation 

 to increase from 29"-38" of arc during 1899 May 20-23. T'l's 

 increasing distance would appear to be partly due to an actual 

 separation of the two portions of the nucleus, but this has not 

 yet been examined sufficiently to be decisive. 



On 1899 June 5 a considerable increase of brightness was 

 noticed by many observers, the nucleus being estim ated by Dr. 

 Hartwig to be 95 magnitude and the whole comet about 5-0 

 magnitude, the diameter of the coma being about 12' of arc. 

 Dr. Schorr recorded that the nucleus appeared to be excen- 

 trically situated. (Aslrotiomische Nachrichten, Bd. 157, No. 

 3747-48-) 



THE CHEMISTRY OF THE ALBUMINS. 



T^IIE albumins, using this term in its widest and most general 

 sense, form almost the last of the great natural groups of 

 substances which have hitherto presented an imjjenetrable 

 front to the attack of the synthetic chemist. With the progress 

 of organic chemistry, some, at all events, of the alkaloids, the 

 sugars and the glucosides have yielded up their secrets of con- 

 stitution and configuration so fully that their synthetic prepara- 

 tion has crowned the labours of the investigator and confirmed 

 the deductions he has drawn from a study of the reactions and 

 transformations of the products found in nature. But the che- 

 mistry of the albumins, in which lie locked up the secrets of 

 animal and vegetable growth, of health and disease, perhaps 

 even of life .and death, has not yet progressed beyond the pre- 

 liminary stages of investigation — -the establishment of criteria of 

 purity and methods of separation, and the study of reactions and 

 decomposition products. These first studies have, indeed, added 

 much of great value and importance to our knowledge of this 

 supremely interesting class of compounds, but the very com- 



NO. 1674, VOL. 65] 



plication of the results obtained has produced rather a feeling of 

 mental bewilderment than one of increased insight and com- 

 prehension. 



In these circumstances the report of a lecture by Prof. KosscI 

 on the " Present Position of the Chemistry of the Albumins," 

 which is contained in a recent number of the Bcrichte, will be of 

 special interest to both physiologists and chemists. The lecture 

 lorms one of that series of addresses on special branches of 

 chemistry, delivered by the foremost of those engaged in active 

 work upon them, which has been for some years one of the most 

 valuable and attractive features of the activity of the German 

 Chemical Society, and one well worthy of imitation. 



From the admirable account of the subject there given, it 

 appears that in several directions important advances have been 

 made, and we propose here to indicate shortly the nature and 

 tendency of these, after first pointing out some of the difficulties 

 which have not yet been overcome. 



In the first place, no entirely satisfactory criterion of chemical 

 individuality has yet been found for the albumins, all the pre- 

 vailing methods which the chemist has been forced to employ 

 for their purification and separation — precipitation by various 

 reagents, coagulation, differences of solubility, and even crystal- 

 lisation—being pronounced insufficient to guarantee the indi- 

 viduality of the product. This is due partly to the colloidal 

 nature of these substances, a property which is most probably 

 conditioned by their enormously high molecular weight, and 

 partly to their great tendency to form loose compounds with 

 other substances, and especially with such as occur along with 

 them in the tissues of plants and animals. 



A second difficulty lies in the great number of different sub- 

 stances belonging to this class which have been prepared, even 

 with the imperfect methods at present at our command, and in 

 the bewildering complexity of the products of decomposition 

 obtained from many of them by such simple means as hydrolysis. 



One instance may suffice to illustrate this point and at the 

 .same time serve as an enumeration of the various chemical 

 groups obtainable from a complicated member of the class. 

 Certain nucleoproteids yield on hydrolysis the following products, 

 each of which represents a different group in the molecule of 

 the mother substance : — arginine, histidine, lysine, leucine, 

 asparaginic acid, glutamic acid, pyrrolidinecarboxylic acid, the 

 purine bases, thymine, phosphoric acid, two groups containing 

 sulphur, and separate groups yielding furfuraldehyde, skatole 

 and Levulinic acid ; most of these groups are, moreover, with 

 great probability contained several times over in a single 

 molecule. 



Fortunately, however, all the albumins are not as complicated 

 as this, and it is by the discovery of simpler members of the 

 class and by a quantitative study of the products of their de- 

 composition — researches almost entirely due to Kossel and his co- 

 workers — that the most substantial advance of recent years has 

 been m.ade. These, the least complex albumins yet known, 

 have been obtained from the spermatozoa of certain fish and 

 have received names denoting their origin, e.g. salmin, sturin, 

 clupein, &c. They possess strongly basic properties, turn red 

 litmus blue and form salts with acids, yet unite with this 

 chemical activity the high molecular weight and colloidal pro- 

 perties of the albumins, and have hence been termed the 

 prolai/iiiics. Their comparative simplicity is, however, shown 

 by the nature of the products formed from them by hydrolysis. 



The more familiar and complex members of the group, such 

 as casein or egg-.albumin, yield on hydrolysis a large number of 

 different j^roducts, which may, however, be grouped in four 

 main classes : — 



( 1 ) A compound capable of yielding urea. This is invariably 

 found in the form of arginine, or guanido-amidovaleric acid, a 

 compound which may be regarded as at the same time a deriva- 

 tive of urea and of diamidovaleric acid. 



(2) The diamidoacids, at least three members of which have 

 been recognised, including the group contained in arginine. 



(3) The monamido-acids, ten or eleven different acids having 

 all been found. 



(4) A number of other products such .is ammonia, furfuralde- 

 hyde, pyrrolidinecarboxylic acid, humus-like substances, &c. 



The proportions in which the representatives of these classes 

 are produced vary greatly for the different albumins, casein, for 

 example, yielding very little arginine (about 5 per cent.) and a 

 large proportion of monamido-acids (75^85 per cent., including 

 at least three or four different aci^s). 



Now the simplest protamines, of which salmin may be taken 



