F 



Oct. 1st, 1887.] 



SCIENTIFIC NEV^^S. 



179 



per gallon ; but, on the other hand, the water of Bala Lake 

 contains only 1-3 grains per gallon. 



We have seen that when milk of lime is added to water 

 containing carbonates, held in solution by the presence of 

 carbonic acid, the latter combines with the lime and all the 

 carbonates are removed by precipitation. Following on 

 this principle. Dr. Clark advocated the softening of water on 

 a large scale by adding milk of lime to it, and this process 

 has been largely adopted. It was doubtless a step in the 

 right direction, but it dealt only with the temporary and 

 not with the permanent hardness of the water, and was 

 therefore incomplete. Several attempts have been made to 

 meet this difficulty, and the best apparatus we know of for 

 the purpose is that made by the Stanhope Company, and 

 illustrated below. In this system soda is added in calculated 

 quantities to the lime-water before it is mixed with the water 

 to be softened. The effect of this is to convert the sulphates 

 into carbonates, and these are precipitated in the same way 

 as the original carbonates present in the water. Originally 

 the mixture of hard water and lime-water was run into large 

 reservoirs, in which the precipitated lime gradually sank to 

 the bottom, the clear water at the top being drawn off from 

 time to time. These reservoirs, however, needed a large 

 space and a considerable outlay, so that filters were tried 

 in order to collect the precipitates quickly, but, although the 

 first cost was then reduced, the working ccst was much in- 

 creased owing to the expense of cleaning the filters and of 

 renewing the filtering media. 



In the apparatus illustrated, the chemical re-agents are 

 mixed in the small iron tanks placed above the clarifying 

 vessels. These tanks and vessels are in duplicate, so that 

 one set may be prepared for work while the other is in use, 

 and in this way the process is not interrupted. 



The water to be softened enters the large external vertical 

 pipe shown in Fig. i, a proper proportion of the liquid con- 

 taining the reagents being admitted at the same time. The 

 mixture in the pipe then enters the bottom of the clarifying 

 vessel which consists of a large rectangular iron casing, 

 open at the top, and contains V shaped trays inclined at an 

 angle of 45°, as indicated by dotted lines in Fig. i. The 

 water then rises slowly, the precipitates are deposited on 

 the trays, and when the water reaches the top of the vessel 

 it is quite clear and fit for use. With a reasonable amount 

 of care, clogging of the apparatus is almost impossible, and 

 it is very easy to manage. The average cost of ihe 

 chemicals required is said to be one penny per 1,000 

 gallons. The apparatus shown in Fig. 2 works on the same 

 principle, but is differently ai ranged so as to occupy less 

 vertical height. 



We all know that when hard water is used, much more 



soap is required lo produce a lather than with soft water. 

 The reason of this is that when the water is hard the salts 

 of lime and magnesia form an insoluble compound with the 

 fatty acid of the soap, which we call curd. This is not only 

 an inconvenience, but is the cause of great waste of soap, 

 which in certain manufacturing processes, such as the wash- 

 ing of wool, for instance, is very considerable. Every 

 degree of hardness destroys in this manner one pound of 

 the best soap for every 1,000 gallons of water, and this is 

 an absolute loss without any compensating advantage what- 

 ever. In a mill using 10,000 gallons of water daily, with 

 10° of hardness, the annual loss in soap (at ?d. per lb.) for 

 300 working days will therefore be ^:^5o ; and for a mill 

 using no,ooo gallons daily, with 15° of hardness the annual 

 loss in soap will be X375- Moreover, there is a further 

 disadvantage in using hard water for work of this kind, 

 because the material is more dull in colour and more rough 

 to the touch than it would be if soft water were used. Tlie 

 need of soft water is, in fact, very great, especially with 

 textile manufacturers of all kinds. 



To all users of steam and hot water it is also of the 

 greatest importance that the water should not be hard, or 

 deposits will be formed in the boilers and pipes, and this 

 will not only cause serious loss and inconvenience, but may 

 also be a source of danger. It is, in fact, eitimated that half 

 the boiler explosions which occur are caused by the scale 

 formed by the precipitates from the water. This scale pre- 

 vents the water from being in contact with the boiler-plates 

 over the fire. The latter become over-heated, there is a 

 sudden generation of steam, and the boiler is unduly strained 

 or burst. We could point out many other disadvantages of 

 hard water, but we have said enough to indicate the im- 

 portance of the subject, and to point to the benefit of using 

 an efficient sofiening apparatus when natural soft water 

 cannot be obtained. 



THE SOURCE OF MUSCULAR POWER. 



IN his presidential address at the recent meeting of the 

 British Association, Sir Henry Roscoe briefly referred 

 to this very important subject, and although his statements 

 were clearly expressed, and were familiar to physiologists, 

 we fear they were too condensed to be fully appreciated by 

 the lay members of his audience. The subject is, however, 

 one of the greatest importance to all, and as Dr. Frankland 

 observes, it is the corner-stone of the physiological edifice, 

 and the key to the nutrition of animals. We make no 

 apology, therefore, for dwelling on such a subject, and 

 for endeavouring to explain the present state of our know- 

 ledge. 



Sir Henry Roscoe reminded us that nearly fifty years ago 

 Liebig presented to the Chemical Section of the British 

 Association a communication in which, for the first time, an 

 attempt was made to explain the phenomena of life on 

 chemical and physical lines. In this paper he admitted the 

 applicability of the great principle of the conservation of 

 energy to the functions of animals, and pointed out that the 

 animal cannot generate more heat than is produced by the 

 combustion of the carbon and hydrogen of his food. 



" The source of animal heat," says Liebig, " has previously 

 been ascribed to nervous action, or to the contraction of the 

 muscles, or even to the mechanical motions of the body, as 

 if these motions could exist without an expenditure of 

 force consumed in producing them." According to Sir 

 Henry Roscoe, Liebig compared the living body to a labora- 

 tory furnace, in which a complicated series of changes occur 

 in fhe fuel, but in which the end-products are carbonic acid 

 and water, the amount cf heat evolved being dependent, 

 not upon the intermediate, hut upon the final products. 



