June 30, 1887] 



NATURE 



209 



pool Astronomical Society will be held at Burlington House, 

 London, on Friday, July 8. 



The problem of protection against yellow fever by inocula- 

 tion seems in a fair way to solution by the Brazilian doctor 

 Freire, who has been seven years at work on the subject. 

 According to a recent account, the number of persons already 

 inoculated is 6524. There died from yellow fever in Rio de 

 Janeiro, between January 1885 and September 1886, 1675 

 persons, of whom eight had been inoculated (in 1884, the method 

 being then imperfect). This gives a mortality of about i per 

 locx) for the inoculated, and i per cent, for the uninoculated. 

 It is remarkable that there has been no epidemic of yellow fever 

 in Rio de Janeiro this year (a thing not known for the last thirty- 

 five years). The microbe of yellow fever is called Cryptococciis 

 xanthogenicus , Dr. Freire gets a culture liquid for inoculation, 

 on the principles of M. Pasteur's methods, and he injects about 

 one gramme of it subcutaneously. 



Experiments have been recently made by S. Leone {Gazelta 

 Chimica Italiana) as to how organic: substances in water are 

 affected by development of bacteria. He used distilled water, 

 to which a little gelatine was added. The organic nitrogen and 

 carbon are changed by the organisms into inorganic compounds, 

 chiefly carbonic acid, ammonia, nitrites, and nitrates. It appears 

 that up to the fifteenth or sixteenth day the ammonia steadily 

 increased, then it decreased till it was quite gone. Meanwhile, 

 nitrous acid appeared ; it increased as the ammonia disappeared , 

 and when this was gone, a formation of nitric acid began, at the 

 cost of the nitrous acid, so that in thirty-five days the latter 

 too was quite gone, and only nitric acid present. If a little 

 gelatine was put in the water which had turned ammonia into 

 nitrates, the reverse process began ; ammonia was formed again, 

 and even directly added nitrate was changed into this. If no 

 fresh gelatine was added, however, nitrites and nitrates were 

 again produced. The author ascertained that the same organisms 

 that in presence of organic substances formed ammonia, in absence 

 of such effected nitrification. 



Profs. Kruss and Nilson, of Stockholm, have succeeded 

 in preparing a double fluoride of potassium and the new element 

 germanium, KgGeFg, isomorphous with the corresponding 

 double fluoride of ammonium and silicon, thus proving most 

 conclusively that this recently discovered element belongs to 

 the silicon, titanium, zirconium, tin, and lead group of the 

 periodic classification. The fluoride of germanium, GeF4, 

 which is not gaseous, but resembles zirconium fluoride, ZrF4, 

 was first prepared by dissolving the oxide, GeO.j, in hydrofluoric 

 acid ; and the double fluoride separated in the gelatinous form 

 on adding the calculated quantity of potassium fluoride. On 

 filtering, however, the salt dried to a crystalline powder re- 

 sembling potassium silicofluoride, but being more soluble than 

 the latter, separated from solution in hot water in beautiful 

 tabular crystals, and from a solution in cold water on evapora- 

 tion over sulphuric acid in pyramid-capped prisms several milli- 

 metres long. Once more the value of Newlands' and Mendele- 

 jeff"'s generalization as an incentive to research is demonstrated, 

 and confidence in its truth inspired, for Mendelejeff" himself 

 predicted that " ekasilicon will yield a double fluoride isomor- 

 phous with the double fluorides of silicon, titanium, zirconium, 

 and tin, of greater solubility than that of silicon ; and the 

 fluoride, like the fluorides of titanium, zirconium, and tin, will 

 not be gaseous." 



A NEW synthesis of uric acid, directly proving its con- 

 stitution, has been effected by Prof. Horbaczewski {Monats- 

 hefte fib- Chemie, May 28, 1887). The reaction is very 

 simple and consists in fusing together i part of trichlor- 

 lactamide, CCI3— CHOH— CO— NH^, with 10 parts of urea, 

 CO(NH2)2, when 15 per cent, of uric acid together with am- 



monium chloride, hydrochloric acid, water, ar.d a few decom- 

 position products are obtained. By a long process of separation 

 and purification the uric acid was obtained quite pure, in crystals 

 exactly resembling those obtained from natural sources. This 

 method of synthesis points to the extreme probability that the 

 constitution assigned by Medicus to uric acid is correct, and 

 shows that it is the di-ureide of acrylic acid. Probably no work 

 has been watched with keener interest than the attempts which 

 have been from time to time made to solve the problem of the 

 constitution of this complex molecule, and it is a matter of great 

 satisfaction to have our knowledge of a substance so widely 

 occurring in animal secretions, and parent of so many derivatives, 

 founded upon a method of synthesis so direct. 



Superficial tension in liquids being, like the magnetic state, 

 an essentially molecular phenomenon, we might expect that it 

 and phenomena depending on it would be modified by action 

 of an intense magnetic field. Prof. Dufour lately proved such 

 an effect by making mercury flow through a horizontal capillary 

 tube placed between the poles of a strong electro-magnet. The 

 liquid describes a parabola, the vein being continuous to a 

 certain distance from the orifice, when it separates into drops. 

 While the magnet acts the parabola is stretched, and the con- 

 tinuous part of the vein lengthens, indicating more rapid flow. 



Attention has been lately called by Herren Kerner and 

 Wettstein, in the Vienna Academy, to two carnivorous plants 

 found in Germany. One of these is the leadwort root {Lathrcea 

 sqiiamaria) which has no chlorophyll, andjpasses for a parasite, 

 as it fixes, with small nipples, on the roots of fruit-trees. The 

 pale stems, appearing in shady moist places in spring, are 

 covered thickly with scale-like leaves, each of which has its 

 upper half rolled back on the back of the lower, leaving a hollow 

 space between. Into this open by small holes from five to 

 thirteen separate chambers, having on their surface numerous 

 tufted hairs and hemispherical horns connected with the vascular 

 bundles. Various small animals get into these chambers, and 

 ere long disappear. From both hairs and horns threads of 

 plasma stream out, when the animals come into contact with 

 them, and lay hold of them. Though it is not exactly proved 

 that the plant benefits by the animals it thus catches, this seems 

 very likely from its general character. It is more remarkable 

 that a plant containing chlorophyll, and existing independently, 

 like Bartsia alpina, should have similar organs for capture of 

 animals, and should feed on such, as the authors assert. The 

 plant forms in autumn underground buds covered with scales, 

 whose lateral borders are rolled outwards, making a hollow in 

 which are organs quite similar to those in the leadwort root. 



The habits of the rainbow trout {Salmo irideus) in their fry 

 stage are in some respects very different from those of other 

 species of Salmonidae. At the present time many thousands of 

 them may be seen in the ponds belonging to the National Fish- 

 Culture Association at Delaford Park, where they were hatched 

 out in the spring from ova sent from California. Instead of 

 moving about in groups or shoals, they isolate themselves from 

 one another, and are to be found in every part of the pond 

 instead of at certain spots or on shallows. Again, the rainbow 

 trout fry are visible within half a foot of the surface of the water, 

 while other varieties hide from view. They appear to be 

 exceedingly voracious, and this may account for their capacity 

 for rapid growth, which exceeds that of their congeners. 



In one of the Selborne Society Letters, issued the other day, 

 the Rev. S. A. Preston, the founder and for many years the 

 President of the Marlborough College Natural History Society, 

 sets forth his ideas as to the best method of promoting the study 

 of natural history in schools. He thinks (i) that each boy 

 should have the elements of two or three branches of natural 



