454 



NA TURE 



[March 9, 1899 



the other two directions, a and h, for which latter the increments 

 are nearly equal. This is analogous to the optical behaviour. 



The amount of cxp,insion along the direction of the axis b is 

 appro.vimately identical for all three sulphates, indicating that 

 interchange of the metals is without influence on the thermal 

 behaviour along this axis. 



The chief of the directional perturbations previously referred 

 to consists of a reversal, for temperatures below 50% of the 

 directions of the maximum and intermediate axes of the thermal 

 ellipsoid for rubidium sulphate, compared with their directions 

 in the potassium and cxsium .salts. The maximum thermal axis 

 is c for the two latter salts, but a for rubidium sulphate. A 

 similar reversal of the direction of the maximum axis of the 

 optical ellipsoid (the indicatrix), the first median line, from cto 

 a, occurs for the same temperatures, in the case of rubidium 

 sulphate. The maximum thermal axis is identical with the first 

 median line in all three salts. 



At higher temperatures the same relations continue to hold 

 for the potassium and CKsium salts, both thermally and optically. 

 Hut owing to the increment of expansion along c being so much 

 greater than for the other directions, the intermediate expansion 

 along c for rubidium sulphate attains equality at 50° with the ex- 

 pansion along a, and beyond this temperature c becomes the 

 maximum thermal axis for this salt, as it is for the other two 

 sulphates. Consequently, at 50° the crystals of rubidium 

 sulphate are apparently thermally uniaxial. At temperatures 

 varying 10' each side of 50' for different wave-lengths of light, 

 they have previously been shown to simulate uniaxial optical 

 properties. The thermal and optical ellipsoids of revolution are 

 not, however, identically orientated, the axis of the former being 

 b and of the latter a. 

 The final conclusion of the investigation, therefore, is that : 

 The thermal deformation constants of the crystals of the 

 normal sulphates of potassium, rubidium, and ca;sium exhibit 

 variations which, in common with the morphological, optical, 

 and other physical properties previously investigated, follow the 

 order of progression of the atomic weights of the alkali metals 

 which the salts contain. 



"Observations on the Cerebro-Spinal Fluid in the Human 

 Subject." By St. Clair Thomson, M.D., Leonard Hill, M.B., 

 and'W. D.. Halliburton, M.D., K.R.S. 



One of the authors. Dr. Thomson, has had under his care for 

 some years a very remarkable patient, in whom, without any 

 history of injury, cerebrospinal fluid dripped continuously from 

 one nostril. Research into the literature of the subject has 

 shown that there are other cases on record which must have 

 been similar, although the true nature of the fluid was not recog- 

 nised. Some of these patients ultimately died from inflammation 

 of the membranes of the brain, which had probably spread from 

 the nose through the opening in the bony lamina that normally 

 completely separates the cranial and nasal cavities. 



The fluid itself is characterised by its clear watery character, 

 its low specific gravity, the small amount of proteid in it, and the 

 absence of albumin, and by the presence in it of a substance 

 which reduces Fehling's solution, but is not dextrose ; the sub- 

 stance is po.ssibly related to pyrocatechin. The contrast between 

 such a fluid, and the mucin-containing fluid of ordinary nasal 

 hydrorrhcea is very marked. 



Analysis of the fluid which escaped in the evenings showed it 

 to be more watery than that collected first thing in the mornings ; 

 the difference is due principally to an alteration in the amount of 

 organic solids. This confirms an observation of Cavazzani on 

 dogs, and is what one would expect, as the decreased capillary 

 pressure during re.st would lessen the rate of exudation of water. 

 The case afforded a unique opportunity to Dr. Letmard Hill 

 to confirm the theories he has advanced concerning the cerebral 

 circulation. He has put forward the view that the rate of secre- 

 tion of the cerebro- spinal fluid, when the cranio-vertebral cavity 

 is opened, depends directly on the difference between the 

 pressure in the cerebral capillaries and that of the atmosphere. 

 At the same time it was shown that cerebral capillary pressure 

 varies directly and absolutely with vena cava pressure. 



On the other hand, cerebral capillary pressure varies directly, 

 but only i>roportionately, with aortic pressure, for l>etween the 

 aorta and the capillaries there lies the peripheral resistance. 



It follows from the above that the easiest methods of raising 

 the cerebral capillar)' pressure in man are ; — 

 (fl) By compression of the abdonien. 



(h) By the assumption of the horizontal posture. In this 

 position, however, the rise of venous pressure may be com- 



NO. 1532, VOL. 5q] 



Densated by the fall of arterial pressure, which normally occurs 

 when the body is at rest. This is, no doubt, the case during sleep. 

 (<•) By straining or forced expiratory effort, with the glottis 

 closed. 



By all these methods the vena cava pres.sure is considerably 

 raised ; and by the last method the venous inlets into the thorax 

 may be completely blocked, and the pressure in the cerebrat 

 capillaries raised to something like aortic pressure. 



It is true that by such a forced expiratory effort the aortic 

 pressure is lowered. Nevertheless, the total effect on capillary 

 pressure is a very great rise, for a fall of aortic pressure of 

 25 mm. of mercury produces a fall in cerebral capillary 

 pressure of less than 5 mm. of mercury, while a rise of vena 

 cava pressure of 25 mm. of mercury produces a rise of cerebral 

 capillary pressure of 25 mm. Hg. 



The figures, which are given in detail in the paper, show 

 that in the present case the flow of the cerebrospinal fluid is 

 accelerated by all the circumstances enumerated, which raise 

 the cerebral capillary pressure. The increase r)f flijw is, more- 

 over, accompanied by a decrease in the percentage of solid 

 matter. 



One of the authors (W. D. H.), in conjunction with Dr. 

 Mott, K.RS., has examined the results of injecting into 

 animals cerebrospinal fluid removed from cases of brain 

 atrophy, especially from cases of general paralysis of the 

 insane. This fluid contains a toxic substance, choline, doubt- 

 less derived from the disintegration of lecithin in the brain. 

 Injection of such fluid into the jugular vein of animals, 

 anxslhetised with ether, causes a marked lowering of arterial 

 blood pressure, which is partly cardiac in origin, but princi- 

 pally due to the local action of the poison on the neuro- 

 muscular apparatus of the peripheral vessels, especially in the 

 splanchnic area. 



The fluid obtained from the present case was also injected 

 in a similar way. (^)uantities varying from 7 to 10 c.c. were 

 injected into the circulation in dogs, but with entirely negative 

 results. Such a quantity in the ease of fluid from a general 

 paralytic would be quite sufficient to cause a marked fall of 

 arterial pressure. 



Mineralogical Society, January 31. — Prof A. H. Church, 

 F.R.S., President, in the ch,air. — On a new mode of occurrence 

 of ruby, in North Carolina, by Prof. John \V. Juild, F.R.S., 

 and Mr. \V. K. Hidden ; with crystallographic notes by Dr. 

 J. H. Pratt. About fifteen years ago, very finely-coloured 

 rubies were found at Cowie Creek, North Carolina, and some 

 of these, according to competent experts, have the colour and 

 brilliancy of the finest .stones from Burma. These rubies are 

 found in gravels and alluvia underlaid by a "saprolitic" 

 material, the product of the decomposition ;// silii of the rocks 

 of the district. The gems are derived, not like those of Burma 

 from a limestone ruck, but from certain basic rocks, such as 

 eclogite, amphiboliie, and hornblende schist, .\ssociated with the 

 rubies are found specimens of " rhodolite," a very clear and fine- 

 coloured variety of garnet having a composition intermediate be- 

 tween pyrope and aimandine. This garnet is often found en- 

 closed in corundum, so that it must belong to an earlier period oJ 

 consolidation. In h.ibit, the corundum crystals of Cowie Creek 

 are very similar to tho.se found at Yogo Gulch and other local- 

 ities where the mineral occurs in rocks of undoubted igneous 

 origin. It is suggested that the rubies of both Burma and 

 Cowie Creek may have originally existed in rocks of basic 

 character of very similar composition. — Experiments on zeolites, 

 by Prof. .\. II. Church, F.R.S. The author describes an ex- 

 periment tending to show that the action of silver nitrate on 

 phillipsite is analogous to that investigated by liichhorn and 

 by Lemberg in the case of other salts on other zeolites. Prof. 

 Church also exhibited numerous specimens of pure blue apatites 

 from Ceylon, which, owing to their beautiful colour, had been 

 mistaken fur sapphires. One of these specimens contained as 

 much as 3 2 1 per cent, of chlorine, but others only 063 per 

 cent, and o 34 per cent. — On the constitution of mineral 

 arsenates and phosphates. II. Pharmacosiderite, by Mr. E. G.J. 

 Hartley. In continuation of his chemical investigation of 

 mineral ar.senates and phosphates, the author gives the results 

 of analyses of pharmacosiderite. From 24 104 per cent, of 

 potash was found in the specimens analysed, and all the Cornish 

 specimens examined contained this alkali. Water determin- 

 ations made with special care showed that the mineral contains 

 eighteen molecules instead of fifteen, as previously supposed. — 

 The specific identity of binnite with tennantite, by Mr. G. T. 



