1844.] 



THE CIVIL ENGINEER AN ARCHITECT'S JOURNAL. 



Ill 



wlietlipr it is not advisable to savf the drainage waters, and after evaporating, 

 by some means, to restore tbem to the soil, as doubtless they must contain 

 these salts, which would be so beneficial to the crops. 



The shrinkacc of soils in dry weather seems to be in proportion to the clay 

 or'orRanic matter present. Clays and peats in drying shrink one-fifth of 

 their bulk. This action is of great utility, by increasing capillary aclion, and 

 by forming conduits, by which the supeiduous water may run off. Of course 

 this does not take place in sandy soils. 



The absorption of heat by the soil during sunshine is very great, some- 

 times raising its temperature 30° or 40° over that of the air. When the air 

 has been at 70' or 80'. the soil has been observed, during sunshine, at 100' or 

 120°. Black lands will rise rather higher in temperature than those of a 

 lighter colour, but not so much so as might have been imagined ; the greatest 

 difference observed having been 10'. When a chalk was observed at 100', a 

 neighbouring black loam was at 110°. The difference of absorption of heat 

 by different colours may be illustrated by placing pieces of phosphorous on 

 three pieces of tin, one with its own surface, one coloured white, and the 

 other coloured black, and placing a hot iron ball between them at an equ.al 

 distance, to represent the sun. The phosphorus will be ignited first on the 

 black, next on the wdiite, and lastly on the metallic surface. Those soils 

 which absorb the quickest, radiate the quickest, and consequently would be 

 coldest at night. 



The subject next claiming attention is the atmosphere, and which here in- 

 troduces an important division of the subject ; for as the soil has Ijeen con- 

 sidered as being the source of the inorganic part of plants, so the atmosphere 

 is considered as yielding to the plant the wdiole of the organic part. Start- 

 ling as this statement may appear, strong arguments will be brought forward 

 to prove its plausibility. The composition of the atmosphere in 100 parts by 

 measure is, 



Nitrogen .... 



Oxygen- .... 



Watery vapour (consisting of oxygen and hydrogen) 

 Carbonic acid (consisting of o,\ygeu and carbon) 



Ammonia (consisting of nitrogen and hydrogen) 



These are the invariable proportions of its constituents, let the air be col- 

 lected where it may, on the top of a mountain or in the depth of a valley, 

 in Europe or in America. This extraordinary uniformity may be accounted 

 for by the property of the difi'usion of gases, by the action of currents, the 

 earth's motion, winds, &c. 



Nearly the whole of the organic part of plants is composed of Ihe four 

 elements, carbon, hydrogen, oxygen, and nitrogen. As all these substances 

 can be found in the soil, that was supposed to be the source from whence Ihe 

 plant derived them. But recent investigations have shown that whilst vege- 

 tables impoverish the soil as regards the inorganic matter, they greatly in- 

 crease the proportion of organic matter in the soil. A fir plant, growing on 

 a dry sandy soil, is continually enriching it nitii humus, by the fall of its 

 leaves and twigs. It is evident, then, thit it must derive the greater part, if 

 not all, of its wood from the air, and it is doubtful whether, for this purpose, 

 the great bulk of the air, the nitrogen and oxygen, contribute any part, or 

 whether it is not due to the water, carbonic acid, and ammonia, which, al- 

 though present in so small a quantity, yet, as will be shown in a future lec- 

 ture, is sufficient for the purpose. These may, by artificial means, be re- 

 moved from the air, the water and ammonia by means of sulphuric acid, or 

 chloride of calcium, and the carbonic acid by lime ; and although the differ- 

 ence could not be detected in breathing or in the burning of combustibles, 

 yet it has been destroyed as regards plants, because there is an entire absence 

 of that whicli maintains vegetable growth, and without which plants cannot 

 form their structures. 



The proportion in which the nitrogen and oxygen exist in the air can be 

 ascertained by abstracting the oxygen ; this can be done by several means ; 

 if fine iron filings be powdered over the inside of a glass vessel, and this 

 stood over water, the iron will combine with the oxygen, or become rusted, 

 and the water will rise in the vessel to take the place of the abstracted 

 oxygen. But it maybe effected more rapidly by burning a piece of phos- 

 phorus in a portion of air confined over water; the phosphoric acid pro- 

 duced dissolves in water, leaving the nitrogen gas pure. If the properties of 

 this gas be then examined, it will be found that it will neither burn nor sup- 

 port combustion or life, that indeed, it is totally inert. If it is w ished to get 

 oxygen gas pure, it cannot be obtained from the air, as there is no means 

 known of removing the nitrogen. It may be procured by heating sulislances 

 which contain a great quantiiy of it, and which will part with a portion of 

 it readily. Such is black oxide of manganese ; which is commonly employed 

 on account of cheapness. For the sake of purity, chlorate of potash is best, 

 or a mixture of the two. The properties of the gas thus obtained are the 

 opposite of those of nitrogen, being very energetic, supporting combustion 

 most vividly, and hurrying respiration to fever and death. Iron and zinc 



wire, heated at one end, and introduced into this gas, burned with great 

 beauty, as do also charcoal and sulphur. Phosphorus burns with brilliancy, 

 such that the eye can scarcely bear. From this it is evident that in the air 

 it Is the oxygen that is the acting principle, and that the nitrogen serves the 

 office of detecting it, so as to make its action on substances immersed in it 

 sufficiently slow. 



The next and lollowing lecture will be devoted to the consideration of the 

 lesser, although as regards plants, the more important components of the 

 atmosphere. 



Fig. I. 



Fig. 2. 



REGISTER OF PATENTS. 



tTnder this head we propose to give abstracts of the specifications of all the most im- 

 portant patents as they are enrolled. If any additional information be required as to any 

 pa'ent, the same maybe obtained by applying to Wr. LAXTON at the Office of this 

 JOtJRNAL. 



IMPROVED WINDOW SHUTTERS. 



Aechibalp IIokn, of Aldersgate Street, Zinc Worker, for " Improvements in 

 the covstruction of windows, and for other purposes.^* — Granted August 15, 1843 ; 

 enrolled February 15, 1814. 



This invention consists in a novel 



_ 1 mode of constructing shutters for clos- 



xg ii [ ~' ing windows and other openings, and 



consists in forming the shutters of thin 

 plates of metal, strengthened at each 

 end, and made to slide in vertical 

 grooves at each side of the window 

 or opening, and are successively depo- 

 sited side by side in a box or chamber 

 provided for their reception. Fig. I, 

 is a transverse section of a window 

 showing the application of this im- 

 provement; Fig. 2, is an end view of 

 some of the plates, drawn on a large 

 scale ; Fig. 3, is a front view of the 

 shutters, shosving the method of rais- 

 ing tliem : a, a, a, are tliin plates of 

 metal, strengthened by means of trans- 

 verse pieces of metal, a' a' at each end i 

 all of which are similar, with Ihe ex- 

 ception of the lower one, which has a 

 piece of metal, b, attached to its lower 

 edge, having a female screw at each 

 end, through which the screws, c c, 

 pass. In Fig. 2, e is a portion of the 

 grove, within which the ends of the 

 plates slide, and //, the box or cham- 

 ber for receiving such plates, which 

 are so formed at their edges, or that 

 part which forms the coupling, that 

 as they are raised in the groove e, they will successively be disengaged, and 

 each succeeding shutter will force the preceding one into the chamber /. It 

 w ill be clearly seen, that on giving motion in one direclion to the screws c c, 



M 



which is effected by means of a winch or handle, g, seen in Fig 1, which im- 

 parls motion by means of a bevel wheel to the horizontal shaft, It, that the 

 metal plates or shutters, a a, will be raised in the groove, and the same will 

 be disengaged successively until the whole, with the exception of the lower 

 one, are deposited iii the chamber ; antl on reversing the motion of the handle, 



