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HARDWICKE'S SCI ENCE-GOSSJP. 



GOSSIP ON CURRENT TOPICS. 

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



PROFESSOR HENRY DRUMMOND has 

 propounded a theory concerning the white ant 

 which is interesting. He states that there can be no 

 succession of crops "without the most thorough 

 agriculture," and that where man is not doing this 

 work, nature employs other agents. Darwin has 

 shown how the soil of England is tilled by earthworms 

 to the extent of having ten tons of dry earth per acre 

 annually transferred from below to the surface, by 

 passing through their bodies and deposited as their 

 casts. But in tropical countries, where the soil is hard 

 baked by the sun during eight or nine months of the 

 year, and too dry for worms to operate, other agencies 

 are demanded, and Professor Drummond finds one of 

 remarkable efficiency in the termite, or "white ant" 

 as it is called, though it is not an ant at all. 



The working termites are blind, and guarded while 

 working by soldiers with eyes. They cannot live 

 above ground on account of their blind helplessness 

 against the many foes whose hunger they are specially 

 qualified to satisfy, but their food is above ground. 

 They eat dead wood, and all kinds of dead vegetable 

 matter, but seem incapable of feeding on living plants. 

 To reach the dead branches of a living tree, they build 

 galleries or tunnels running up the stem, these tunnels 

 being made up of minute pellets of earth brought from 

 below and cemented together. As is well known, 

 their ordinary structures assume great magnitude, 

 mounds, cones, and strange fantastic edifices all 

 composed of subsoil brought upwards. This action 

 is doubtless similar to that of our earthworms, but there 

 is a serious difference otherwise ; as the earthworms 

 work for themselves, and others at the same time ; and 

 their wages are very small. The damage they do to 

 man and other animals is barely measurable, but the 

 termite is a terrible devastator, he levies black mail 

 on the food, the dwellings and furniture of man 

 (under favourable circumstances a colony can devour 

 a four-post bedstead in twenty-four hours), and of 

 other animals, to such an extent that, in spite of their 

 subsoil ploughing, their extermination from the face 

 of the earth would doubtless be voted a great bless- 

 ing by an overwhelming majority of men and other 

 tropical anim als, if a fair plebiscite could be taken. 



The state of the Lea, of the Thames, and I may add 

 of the Brent in my own neighbourhood, during the 

 past summer months, shows how largely we are 

 dependent on the flushing action of rain for the 

 removal of sewage poison under our present arrange- 

 ments. This flushing action of rain-water is evident 

 to everybody, but there is another action that is 

 invisible, and therefore far less widely understood. 

 I refer to the purifying action of the oxygen contained 

 in water that has been freely exposed to the atmos- 

 phere. A gallon of such water, at the winter 

 temperature of 45 Fahr., contains 2 '2 cubic inches 



of oxygen ; at summer temperature of 70°, I '8 cubic 

 inch. This oxygen is a most efficient disinfectant ; 

 its efficiency in effecting complete purification is 

 simply a question of quantity. 



Thus the mere dilution of sewage does something 

 towards its purification, and in addition to this the 

 mixture of water and sewage picks up more oxygen 

 as it travels along the course of a river. It has been 

 estimated that water containing 32 per cent, of sewage 

 is completely disinfected in the course of a journey of 

 one mile, but I may qualify this estimate by adding 

 that the water must be very shallow for this to occur. 

 The case is very different where the sewage of London 

 mingles with the deep water of the lower Thames. 



Old-fashioned treatises on Natural Philosophy 

 included "porosity" as one of the general "properties 

 of matter." Thus Dr. Lardner says, "there is no 

 substance so dense as to be divested of pores. The 

 celebrated Florentine experiment, performed at the 

 Academia del Cimento in 1661, and often repeated 

 since that time, with the same result, showed that 

 gold itself has sufficiently large pores to admit the 

 particles of water to pass through them." This expe- 

 riment was made by filling a globe of gold with water, 

 closing it with a screw, and then squeezing down the 

 globe with a powerful screw. The diminution of its 

 capacity caused a forcing of the water through its 

 pores, the water appearing on the outer surface. 



Further experiment, however, shows that such 

 pores are merely accidental, due to the fact that the 

 metal was cast, and to the conditions of the cooling 

 of cast metal. By hammering or rolling the gold, 

 such pores are filled up. In the " Gazetta Chimica 

 Italiana " is an account of experiments by Sig. A^ 

 Bartoli, proving the absolute impermeability of glass 

 to gases under a pressure of 126 atmospheres. 



As everybody knows, a very large proportion of the 

 show at the "Inventories" contained no element of 

 new invention whatever, and these mere shop-front 

 cases by their bulk and pi eminence, dwarfed the 

 really interesting demonstrations of the triumphs of 

 modern invention. Among these are the coal-tar 

 products, of which alizarin may be named as one of" 

 the most remarkable and important. Mr. S. B. 

 Boulton, chairman of the British Alizarin Company, 

 states that the yearly consumption of 20 per cent, 

 strength alizarin in Great Britain now amounts to 

 3400 tons. A ton of this does the dyeing work of 

 eighteen or twenty tons of madder root. At the 

 lowest estimate the alizarin we use in Britain represents 

 61,200 tons of madder. The cost of this at the 

 average of old prices (from i860 to 1876) would be 

 ,£2,907,000, while that of the artificial alizarin is 

 £456,960, thus effecting a saving of nearly two and a 

 half millions per annum in the mere dyeing of some 

 of the colours of some of our textile fabrics. Alizarin 

 is not an imitative substitute for the tinctorial prin- 

 ciple of madder, but a production from coal tar of the 

 actual thing itself. Its production was due to no 



