MISCELLANY 



6 37 



The primary state of all the tissues of 

 the plant is the condition of simple cells, 

 each of which is, in a certain sense, an in- 

 dependent body, having its own life-work 

 and history in the complicated mass of 

 which the tree is composed. All extension 

 of the tree in any direction is made through 

 the medium of cell-growth and cell-modifi- 

 cations, and, wherever there is cellular tis- 

 sue in a state of vitality, there may be cell- 

 multiplication whenever material for growth, 

 i. e., sap in different stages, is brought into 

 contact with such tissue. 



In the case of the pine-stumps alluded 

 to, the medullary rays of the recent wood 

 retain their vitality, and, when the sap rises, 

 it is transmitted through these rays and 

 through the interspaces of the woody matter 

 to the surface beneath the bark, these being 

 appropriated to the organization of new 

 cells whose walls are thickened by con- 

 tinuous secondary deposits, as in the normal 

 formation of woody tissue. Of course, the 

 amount of this woody formation will be 

 limited, from the deficient supply of sap 

 and want of concentration which it would 

 obtain by passing through the leaves. 



Puncturing the Pericardium. The peri- 

 cardium, or membranous sac surrounding 

 the heart, sometimes becomes so filled with 

 liquid that the movements of that organ are 

 impeded. This is called dropsy of the 

 heart. The surplus fluid may be relieved 

 by the introduction of a trocar into the sac, 

 but the operation is regarded as extra 

 hazardous. Dr. Chairou, of the Paris Acad- 

 emy of Medicine, has tried a new method of 

 treating the disorder in question. A young 

 soldier just recovered from a pleurisy was 

 found presenting all the symptoms of dropsy 

 of the heart. The physician made a punc- 

 ture into the pericardium with a capillary 

 needle, and sucked out a considerable quan- 

 tity of thick sero-sanguineous liquid, which 

 soon became coagulated. The following 

 morning the patient was pacing the corridors 

 of the hospital in the very best of spirits. 



Slag as a Building -Material. " What 

 shall be done with the slag ? " is always a 

 very urgent question for the proprietors of 

 iron-works. Many are the plans which have 

 been proposed for the utilization of this 



waste material, but, if we are to judge of 

 their value by the amount of slag utilized, 

 it must be confessed that they do not help 

 to answer the iron-manufacturers' question. 

 And yet many of the processes for the con- 

 version of slag into a material for building 

 would seem to promise very fair results. 

 Mr. S. Egleston lately read a paper before 

 the American Institute of Mining Engi- 

 neers, in which he gives a history of these 

 processes, stating at the same time, in a few 

 words, the salient peculiarities of each. 

 After recounting the failures which attended 

 the first efforts, the writer sets forth the 

 process followed in Kbnigshutte, Silesia. 

 There the slag is run from the furnace into 

 a hemispherical basin on wheels, the bottom 

 being strewed with sand or fine coke-dust to 

 the depth of an inch. It is then drawn to 

 the place where it is moulded into bricks. 

 The slag and sand having been mixed to- 

 gether till most of the gases have escaped, 

 the whole is pressed into a mould, and 

 punctured frequently to let out the gas. A 

 close-fitting cover then compresses it. The 

 red-hot brick is next taken to the kiln, cov- 

 ered with powdered coal, and left to anneal. 

 Four men make 500 bricks in five hours. 

 In Silesia these bricks cost 25 per cent, less 

 than ordinary bricks. The lead-slag of the 

 furnaces in the Hartz Gebirge gives bricks 

 of inferior quality, being very brittle. A 

 Belgian engineer, M. Sepulchre, was the 

 first to successfully transform slag into a 

 stone which could be generally used. He 

 caused the slag-channels to terminate in an 

 excavation, the sides of which had an in- 

 clination of 30. This steep inclination 

 causes the section of the pits to increase 

 very rapidly, allowing the solid crust on the 

 surface of the liquid slag to rise with it 

 without being attached. The mass takes 

 from five to ten days to cool. The product 

 is a stone which, rather soft at first, grows 

 hard on exposure to air. Slag suitable for 

 such treatment should contain from 38 to 

 44 per cent, of silica. Experiment shows 

 that stone of this kind made from the slag 

 coming from white iron can bear a pressure 

 of 242 kilogrammes (500 pounds) to the 

 square centimetre (one-third of an inch N ' 

 without fissure. If from gray iron, it will not 

 crush at a pressure of 405 kilogrammes. It 

 is, therefore, stronger than the best marble. 



