7«/k3I, i879] 



NATURE 



Z^i 



two curves shows -what becomes of the water which falls 

 on the naked earth, -without vegetation, distinguishing 

 between what returns to the atmosphere by evaporation, 

 and what penetrates the subsoil which is permeable or 

 drained. Another atmograph gives similar indications for 

 a soil covered with various plants ; but the latter being 

 sheltered from the wind, ought to be moistened according 

 as is necessary. Fig. 4 represents only the register of the 

 atmograph. a is the lower part of the stem which is sus- 

 pended to the extremity of the arm of the balance, in 

 which is placed the mass of earth. A second lerer arm, 

 be, follows and amplifies the movements of that stem 

 which it inscribes on the vertical cylinder covered with 

 paper blackened with smoke. This same stem bears a glass 

 test-tube, d, containing mercury, in which is a fixed glass 

 tube e. The diameter of this stem is so calculated that 

 the point c traverses 100 millimetres for each millimetre 

 of water gained or lost by the mass of earth. In calm 

 weather we may thus appreciate the iggth of a milli- 

 metre ; but when the atmosphere is disturbed, the vertical 

 components of the wind cause the needle to oscillate, thus 

 interfering with the. precision of the readings. 



The anemograph (Fig. 5) gives us, at once, the direc- 

 tion of the wind and its mean rate per hour. Eight 

 electro-magnets communicating electrically with the sec- 

 tors arranged on the vane according to the eight principal 

 points of the compass, can, by acting singly or two and two, 

 record the winds for sixteen directions, which may be re- 

 garded to be sufficient for the wants of meteorology. A 

 ninth electro-magnet is acted on each time that the 

 Robinson drum shows a length of one kilometre traversed 

 by the wind. The toothed wheel b then moves one divi- 

 sion, and its movement is transmitted by the satellite wheel 

 (/ to a third toothed wheel, c, on the axis of which is rolled a 

 thread, cp. The point which marks the velocity then ad- 

 vances I mm. towards the left. This effect is produced 

 during one hour for each kilometre traversed by the wind ; 

 but at the end of each hour the needle of the clock 

 establishes an electric contact ; the satellite wheel, d, is 

 lowered ; the wheel, c, becomes free ; and the weight, /, 

 restores the metallic point to its starting-place. 



Fig. 6 presents a specimen of the curves traced by the 

 registers from June 28 to July 3, 1878, reduced to one- 

 third of their natural size. Beginning at the top, we find 

 first the two curves, t n and t b, which together furnish 

 the actinometric data; tn is the curve of the black thermo- 

 meter, TB that of the silvered. The two following curves, 

 T S and T c, give the temperature of the surface of the 

 ground without shade ; T S corresponds to the ground 

 thermometer ; t c gives the correction to be made in the 

 ordinates of the first. The two curves, T and tm, are 

 those of the dry and wet thermometers ; besides the tem- 

 perature of the air in the shade, they give its hygrometric 

 degree and the elastic force of its vapour. H is the 

 curve of barometric pressure. 



Underneath are eight straight lines corresponding to 

 the eight principal directions of the wind ; the vertical 

 lines which rest on them indicate the directions in which 

 the wind has blown. Further down are shown the velo- 

 city, V, of the wind in kilometres per hour. 



The last curve, p E, is made by the atmometer ; the 

 increase in a vertical direction of this curve marks rain ; 

 the decrease marks evaporation. Notwithstanding the 

 frequent and at one time very copious rains, the earth, on 

 July 3, had very nearly resumed its weight of June 28. 

 Finally, the last line is the datum-line on which the hours 

 of the day are marked. 



i 



- GERMAN PHYSIOLOGICAL CHEMISTRY^ 



AS our general knowledge of nature increases, the 

 ■^*; possibility of individual knowledge decreases ; the 

 variety of discovery, the immense number of investi- 



* From Hoppe-Seyler's "Zcitschrift iiber physiologische Chemie.'* 



gators, and the innumerable details which they accumu- 

 late in their respective branches of science, preclude the 

 possibility of a modern " admirable Crichton." Werner's 

 sigh, "True I know much, but yet I would know all," has 

 been long acknowledged as an aspiration incapable of 

 fulfilment, even supposing him to Umit his desire of 

 knowledge within the bounds of what is already known. 

 To know " something of everything, and everything of 

 something," is all that can be hoped for ; day by day 

 each science advances with such rapid strides, that one 

 brain is incapable of grasping more than the general 

 principles of one science ; and any man who aims at 

 enlarging the domain of science by fresh discovery, must 

 content himself with confining his attention to a small 

 corner, and by patient industry and indomitable persever- 

 ance seek to elicit some new facts. 



Such, expressed in general terms, is the drift of the 

 preface to Hoppe-Seyler's " Zeitschrift fiir physiologische 

 Chemie." It seldom happens — unfortunately too seldom 

 in this country — that medical men have more than a 

 smattering of chemistry. A very low standard of che> 

 mistry is required for a medical degree, comprising a 

 superficial knowledge of inorganic chemistry, chiefly of the 

 non-metals ; the merest smattering of organic chemistr);, 

 and ability sufficient to detect the acid and base in 

 simple salts — such are the qualifications in chemistry 

 necessary for graduation in medicine. When the 

 student, following out the prescribed course, comes to 

 attend lectures on physiology, and hears — almost always 

 for the first time — the names of the various principles 

 contained in the animal fluids, in the brain, in the liver, 

 and in the muscular tissue, they fail to convey any definite 

 idea to his mind, and he is utterly unable to comprehend, 

 or even to form an idea of the reactions which take 

 place in the animal organism. In Germany this state of 

 things has been recognised in many universities, and 

 special professors of physiological or animal chemistry 

 have been appointed ; these professors are not merely 

 teachers, but are engaged in the active extension of their 

 branch of science ; and it is to facilitate the interchange 

 of ideas between them, and to afford a medium in which 

 the results of their investigations may be brought to- 

 gether, that Hoppe-Seyler has undertaken the editorship 

 of this journal. 



One noticeable feature of the investigations of German 

 physiological chemists at present, is the attention devoted 

 to ascertaining the changes which food undergoes in 

 passing through the system. At least six memoirs on the 

 subject are to be found in the nine published numbers d 

 the journal, comprising the work of a year and a half. 

 The methods and results of these experiments are worthy 

 of a short description. 



The food which we eat consists for the most part of 

 carbon, hydrogen, and nitrogen ; all food, however^ 

 does not contain nitrogen ; starch, sugar, and fat are 

 devoid of that element. The carbon and hydrogen, 

 after being absorbed by the tissues, and performing work, 

 are cast off as waste material, partly by the lungs, in the 

 form of carbonic acid and water- vapour, and also, to a 

 much smaller extent, in the urine. An almost inappre- 

 ciable amount of nitrogen escapes by the lungs ; by far 

 the largest portion passes into the urine in combination 

 with hydrogen and carbon, in the form of urea— a white 

 crystalline body. Now this substance, urea, possesses a 

 chemical, as well as a physiological interest. It was 

 formerly supposed that all chemical compounds could be 

 divided into two grand classes : inorganic bodies, such as 

 could be prepared from purely mineral matter; and 

 organic bodies, those existing only in a living organism, 

 or obtained from these compounds by a process of de- 

 composition. It was, therefore, imagined that an in- 

 surmountable barrier separated the two classes. Urea was 

 ranked as an organic substance, for it had never been 

 obtained except from the organism, till Prof. Wohler, of 



