8S 



HA RD WICKE'S SCIENCE- G OSSIP. 



Cutting Glass Vessels. — The problem of 

 making a clean cut round a glass tube of considerable 

 diameter, or round a bottle or flask, is one that 

 ■continually vexes the practical worker in a chemical 

 laboratory. A number of books supply a prescrip- 

 tion which the bookmaker has copied very faithfully 

 from his bookmaking predecessors, viz. that a piece 

 of string is to be passed round the bottle or flask, 

 and then soaked in spirits of wine or turpentine and 

 kindled. According to the books, a clean cut will 

 be made corresponding to the string, if the bottle or 

 flask is now suddenly cooled by plunging it in water. 

 According to the experience of all who have tried 

 it, the glass is either cracked in wild random, or it 

 remains unaffected. Perhaps once in fifty times 

 success may be achieved by accident. 



Another and far better method has been recently 

 described by E. Beckmann. First a scratch is made 

 with a file, and this is done carefully in the required 

 -direction. At both sides of this, pads of wetted 

 filtering (i.e. blotting) paper are wrapped round the 

 •object, leaving a space of about |th of an inch 

 between them. The flame of a Bunsen burner or 

 gas blowpipe is applied to the space, starting from 

 the scratch and running round. The crack will 

 follow the flame midway between the two pads. I 

 may add that tubes up to about an inch in diameter 

 are cut very easily by simply notching with a "three 

 square " file, and then breaking as one would break a 

 stick, but with a pulling force combined with the 

 bending. This is familiar to all who work in labo- 

 iories, but not so to outsiders, though a very useful 

 " wrinkle " for many outside purposes. 



Economical Production of the Alkaline 

 Metals. — Sir Humphry Davy discovered the 

 metals of the alkalis, sodium and potassium, by 

 separating the oxygen from soda and potash with the 

 aid of a very costly and powerful voltaic battery. 

 Purely chemical methods have since been adopted, 

 the reducing power of heated carbon being the chief 

 agent. In my boyish days of chemical experimenting, 

 or rather chemical trickery, I paid at Dymond's in 

 Holborn one penny per grain for potassium, or at the 

 rate of £2 per oz. troy. It was then reduced 

 chemically. Its present price is 5-r. to 6s. per ounce. 

 Sodium about 10s. per lb. 



Mr. H. Y. Castner has recently devised a method 

 •of producing these alkaline metals which promises to 

 cheapen them considerably. If it is commercially 

 successful, the results will be important, as the metal 

 sodium is used in the reduction of other metals, such 

 as magnesium, aluminium, &c. This method con- 

 sists in mixing iron that has been reduced in a finely 

 divided state by hydrogen or carbonic oxide, with tar 

 and coking the mixture ; then grinding the coke and 

 mixing it with caustic soda or potash. This is placed 

 in a cast-iron crucible and heated in a specially 

 constructed furnace. The alkali is reduced to the 



metallic state, and the metal, which is volatile at a 

 high temperature, is distilled over. In this process 

 the alkali is submitted to the reducing action of 

 iron and carbon, both of which have been previously 

 used separately. Gay-Lussac and Thenard used iron 

 turnings heated to whiteness as early as 1808. I can 

 only speak theoretically, having made no experiments 

 on Mr. Castner's method nor seen it in operation, 

 but from such theoretical point of view, it appears 

 most promising. 



ASTRONOMY AND METEOROLOGY. 

 By John Browning, F.R.A.S. 



DR. WARREN DE LA RUE, who was the first 

 to photograph astronomical objects successfully, 

 informs me that some excellent photographs have 

 been obtained of Jupiter. When I have had an 

 opportunity of inspecting them, I will give some 

 further particulars. 



The Liverpool Astronomical Society has published 

 a Memoir on " Photometric Photometry," which con- 

 tains a catalogue of 500 stars taken with a stellar 

 camera 4J inches diameter, mounted equatorially. 



The Rev. J. S. Perry, of Stonyhurst Observatory, 

 Lancashire, in a communication on the Chromo- 

 sphere in 1 886, says: "During the past twelve 

 months the Chromosphere has been measured more 

 frequently than in any year since 1S80, and the 

 results should be in consequence more trustworthy. 

 The mean height of this gaseous envelope does not 

 vary much from year to year ; but the prominences 

 that spring out of it have scarcely attained in 1886 

 the height of preceding years, and their number and 

 extent is much diminished." 



In April Mercury will be a morning star, situated 

 in Pisces. Venus will be an evening star throughout 

 the month ; in Aries until the 10th, when it will 

 enter Taurus. There will be no occultations of 

 interest. 



Meteorology.- -Though fogs and mists have been 

 plentiful, yet outside the region of the Metropolis 

 the amount of sunshine in February was much 

 above the average. In the north-east of England 

 and over the Midland districts, the number of hours' 

 sunshine for the month was 41 in excess of the 

 average number for the past seven years, and in the 

 east of England, the excess amounted to as many as 

 51 hours. 



February was drier than" usual, though, contrary 

 to the generally received opinion, it is on the average 

 almost the driest month in the year. In London 

 there was not one-third of the average quantity of 

 rain ; and in Mid-Devon the rainfall was less than 

 one-tenth of the average. In the neighbourhood of 

 the Metropolis there has not been so dry a February 

 for twenty-five years. 



