HA RD WICKE' S SCIENCE- G OS SI P. 



at Equihen, the work is done by Orchestire. No ex- 

 planation of the difterence is supplied, but I venture 

 to suggest that, in the case of Boulogne, all but very 

 hardy filth-eating animals must be killed by surfeit 

 if they approach the harbour. At Le Portel there is 

 one main sewer which is uncovered as it flows into 

 the sea. I have seen the picturesque fisher-wives 

 busily engaged washing their clothes at its outlet, I 

 suppose they find that the ammonia softens the 

 water. If Nassa objects to soap it would avoid this 

 locality. The other places named are farther away 

 and, therefore, may be the habitat of animals that are 

 not sufficiently hardy to endure the aroma of the " eau 

 de Boulogne " which is washed into the sea when the 

 harbour is flooded by the Liane. 



Rock-formation under Pressure. — The re- 

 searches of W. Spring are throwing more and more 

 light on the physics and chemistry of geology. He 

 showed some time ago that a mixture of copper and 

 zinc filings may, by simple compression, become 

 completely interfused and form brass ; that lead and 

 tin may thus form pewter, and fusible alloy may be 

 similarly formed by subjecting a mixture of its 

 constituents to pressure. Also that sulphides of 

 alkalis and alkaline earths may be similarly formed. 

 It was previously assumed that fusion by heat was 

 necessary for effecting such combination. 



He has recently continued such experiments by 

 operating with moistened substances, submitting them 

 to a pressure amounting to 6000 atmospheres, i.e. to 

 about the pressure to which the crust of the earth is 

 subjected at a depth of 60,000 to 70,000 feet. With 

 all the metals the moisture exerts a retarding action, 

 but with soluble substances that give a solution 

 having less bulk than the undissolved materials the 

 conglomeration is assisted by the moisture, while with 

 substances that give a solution of greater volume than 

 the sum of the solid and its solvent it is retarded. 



Substances of the first of these two classes have 

 their solubility in water increased by pressure, while 

 those of the second, suffer a diminution of solubility 

 by pressure. Insoluble substances do not show such 

 marked differences under pressure in the wet and dry 

 state, but in some cases among these the water assists 

 the conglomeration. 



A little reflection will show the bearing of these 

 researches upon the formation of rocks and minerals 

 of all kinds, seeing that in the subterranean laboratory 

 of nature pressure is always operating, and therefore, 

 our superficial laboratory results are modified accord- 

 ingly. Mr. Spring's researches are, in fact, opening 

 up a new chemistry, modifying and even contradict- 

 ing some of the laws induced from our ordinary 

 laboratory phenomena. One of these is the supposed 

 law, that chemical combination cannot occur between 

 dry solids, as familiarly illustrate/I by the fact, that 

 dry carbonates of Soda or potash may be mixed in a 

 state of powder with dr>' tartaric or citric acid with- 



out combining, while they combine with effervescence 

 immediately they are dissolved or even wetted. 



It appears that the agency of water in such cases 

 does no more than to bring the substances into 

 contact ; that the contact, if effected by pressure, has 

 the same effect. If dry sulphate of baryta and 

 carbonate of soda are compressed, a reaction sets in, 

 which is greatly accelerated by heat, and other new 

 and curious chemical reactions may be produced 

 under pressure. Mr. Spring is proceeding with 

 further investigations. 



Dyes from Sea-weed. — Mr. F. Nettlefold has 

 recently communicated to " The Chemical News " 

 (vol. Iviii. page 15), some interesting results obtained 

 by nitrating alginic acid, a sea-weed product. He 

 thus obtains a light yellow substance, which is in- 

 soluble in water, but which by treatment with 

 alkalis yields a brown solution. This alkaline solu- 

 tion, especially when the alkali used is ammonia, 

 dyes cotton directly, without any mordant, and 

 produces a fine " Bismarck brown," which resists 

 soap, and is said to excel many of the aniline colours, 

 the depth of shade being considerable and of great 

 intensity. This dye differs from the aniline dyes in 

 having little affinity for wool, either mordanted or 

 unmordanted. 



This may be the beginning of much useful work, as 

 the dye is so especially applicable to cotton. It 

 seems to be generally the case where any one very 

 decided colour may be brought out, others are obtain- 

 able by modified processes. It will be a great boon 

 if we can turn the vast accumulations of sea-weed on 

 our shores to good account as raw material for 

 chemical manufacture. 



Pig Feeding. — German chemists and farmers are 

 doing a great deal of useful work in the feeding of 

 animals scientifically, i.e. by weighing different kinds 

 of food and carefully recording results. N. J. Fjord, 

 by thus using corn, skim milk, whey, &c., as pig-food, 

 comes to the following conclusions, isl, that the 

 common opinion that pigs make more profitable use 

 of their food when it is largely diluted with water— as 

 in ordinary pig-wash — is fallacious ; 2nd, that although 

 confining pigs produces more increase of weight than 

 allowing them to run in the sty-yard, he thinks they 

 are thus rendered more liable to disease. This is not 

 new. I have heard the same opinion exi^ressed by 

 English farmers ; it is in fact almost self-evident, but 

 unfortunately many pig-feeders care for nothing 

 beyond obtaining weight, whether the fattening be a 

 healthy growth or a result of disease. Judging from 

 the panting specimens commonly exhibited at our 

 cattle-shows, I suspect the judges who award the 

 medals are equally indifferent. I may safely venture 

 to affirm that they rarely or ever apply the stethescope 

 to their victims. 



The 3rd conclusion of this experimenter is that 12 



