170 



HARDWICKE'S SCIENCE-GOSSIP. 



spines. In another variety, 0. rosttla, the minute 

 spikes under well-adjusted conditions of magnification 

 and illumination are objects of extreme elegance ; 

 composed of a hard brittle substance of brilliant 

 transparency. These glassy structures are observed 

 in great perfection and variety of form throughout 

 the entire class of Echinoderms, and known as 

 Pedicellarias, arming the tips of the tubular feet of 

 the true star-fishes and Echini, fulfilling in some 

 instances the functions of grappling irons ; or as 

 spicules as found in the genera Holothuria, Synapta, 

 Chirodota, imbedded in the tissues in the form of 

 perforated plates, circular disks, spikes, and' curved 

 points, aiding in every instance some supporting or 

 locomotive power ; but under whatever conditions 

 these glassy structures are placed, they invariably 

 retain a peculiar grace of configuration, and a typical 

 principle of uniformity. 



In securing living Ophiuridce, the greatest precau- 

 tion is necessary, as under the slightest interference, 

 they immediately shatter themselves into fragments, 

 leaving only the central disk. Sudden death by 

 immersion in fresh water will secure them intact. 

 Dead and desiccated specimens, with the rays attached 

 may be found on some coasts in drift sand, but their 

 beauty is always impaired by abrasion. 



Professor Edward Forbes, in his delightful "His- 

 tory of British Star Fishes," refers to the precautions 

 necessary to obviate the suicidal and dislocating 

 propensity of the brittle star-fish, and how to capture 

 it in its entirety. He gives, in his learned and 

 amusing volume, a graphic and ludicrous description 

 (often quoted) of one of his particular failures ; 

 curiously enough, the rich humour of this passage 

 was incorporated au serienx by a learned German 

 naturalist, in his work on the same subject. 



Crouch End. 



GOSSIP ON CURRENT TOPICS. 

 By W. Mattieu Williams, F.R.A.S., F.C.S. 



AN interesting experiment has been made, and is 

 now in progress as a practically successful 

 process, in disposing of the sewage of Buxton (Derby- 

 shire), 100,000 gallons of which have to find their 

 way in some condition to the Wye, a little river 

 which in dry weather becomes a half-and-half mixture 

 when the sewage is added to it. The necessity for a 

 remedy was of course urgent ; many schemes were 

 tried and abandoned, until the idea of mixing the 

 sewage with a natural chalybeate water flowing from 

 a disused colliery was carried out. The water con- 

 tains sulphate of iron, magnesia, alumina, lime, and 

 soda, besides some carbonate of iron and silica. The 

 chalybeate water added alone partially purified the 

 sewage, but by adding lime to it before mixing with 

 the sewage the purification was effectual to the extent 



of producing a clear effluent from which ij of the 

 original organic ammonia was removed, and f of the 

 free ammonia. The chemical details, which are very 

 interesting, but too much for quotation here, will be 

 found in a paper read at the Society of Arts, by 

 Dr. Thresh, and published with report of discussion 

 upon it in the Society's Journal of May 22. 



The total cost of thus dealing with the sewage is 

 £275 per annum, covered by a rate of \\d. in the £. 

 If the precipitated sludge is rendered marketable for 

 manure, as it should be, this may be reduced con- 

 siderably. The chalybeate water was previously a 

 nuisance, owing to its ochreous deposit in the river. 

 The two nuisances now neutralise each other ; and 

 the condition of the river is actually improved by the 

 sewage and lime. Twelve grains of slaked lime to 

 the gallon of mixture is the mean quantity added. 



At the meeting of the Chemical Society, June 18, 

 Mr. R.J. Friswell stated the results of eleven months' 

 laboratory experience with toughened glass beakers, 

 made according to De la Bastie's patents. They 

 were by no means satisfactory. 



Of twenty beakers two burst spontaneously ; one, 

 when hot water was poured into it ; six became 

 useless from fissures and exfoliation ; three were 

 broken by unknown means, and eight remained in 

 good condition. They were supposed to bear heating 

 over the flame of a rose burner while supported on 

 wire gauze, as the best Bohemian beakers do, but one 

 having burst when hot water was poured into it this 

 severe test was not applied. 



The fissures and exfoliation were curious, the 

 fissures "so close together and running so completely 

 over the surface of the beaker that it had the ap- 

 pearance of being covered with a tissue of spider's 

 web." Mr. Friswell's conclusion is that " taking 

 into consideration the loss of confidence caused by 

 the high percentage of spontaneous bursting, it may 

 be said that toughened glass is a complete failure in 

 the laboratory." 



The cutting of bottles and glass tubes is a labor- 

 atory operation of much economic utility and some 

 difficulty. Small tubes are easily and quickly cut by 

 simply notching with a triangular (" three square") 

 file and applying a binding strain combined with a 

 pull, but when the tube is large this method fails. 

 There is another method described in some books, 

 that of passing a piece of string round the tube, 

 soaking the string in alcohol or turpentine, and then 

 lighting it. According to the aforesaid books this is 

 very easy, but those of my readers who have tried it 

 know better. A modification is now proposed which 

 appears to be really effectual. A fine iron or plati- 

 num wire is wound round the tube, a current 

 of electricity is passed through this, making it red 

 hot or nearly so ; then it is cooled with water, and 

 the heat being purely local, not outspread as by the 

 flaming string, a clean cut is made, My own ex- 

 perience suggests an improvement on this, viz. to 



