234 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



I AUGVST, 



CHEMICAL COMPOSITION OF WATER. 



Professok M'ay, Consulting Chemist of the Royal Afjricultural 

 Souictv of EiiglatuI, delivered a lecture before the members, at 

 their House, in Hanover-scjuare, on Wednesday, the 19tli of June, 

 "Oh Variatiunii in the Chemical Composition of Water, an affecting 

 its Ayrieultaral Uses." 



Tlie Professor commenced his lecture by statinp;, that he intended 

 on that occasion to call the attention of the members to three 

 important heads of inquiry connected with Hater; more with a view 

 to elicit from them practical illustrations founded on their indivi- 

 dual experience, than to offer anytliiuf; particularly novel or estab- 

 lis)ied. These heads of inquiry were the following', namely — 1. On 

 ■W'ater for Steam and other Boilers: the means of ascertaining its 

 comparative suitableness for that [lurpose, and of counteracting its 

 tundency to incrustation. 2 On Water for Irrigation: its chemical 

 impregnation, and the theory of its action. 3. On the influence 

 of \Vater, obtained under different circumstances, on the health of 

 Cattle, Horses, and other live-stock on a farm. He remarked, that 

 as the first head of inquiry related to the mechanical and chemical 

 agency of inert matter, its details came within the range of 

 analytical investigation; and he would be enabled to speak with 

 much confidence on the facts he had to bring together under it; 

 but as the other two heads included a reference to local circum- 

 stances, and to the influence of the vital operations of vegetation 

 and animal physiology respectively, in the production of results, 

 wiiat he had to say on these points would be much less decisive, 

 and advanced more for the purpose of seeking than for giving 

 information. 



I. Water for Boilers. — The water from the climds reaches the 

 earth almost pure in a chemical sense, as a homogeneous liquid, 

 composed of the elements oxygen and hydrogen. It was distilled 

 from the sea and land, and from the leaves of vegetables in a state 

 of purity, and formed clouds; from which it again fell at intervals 

 to the earth through tlie atmosphere, bringing with it only very 

 minute traces, varying according to circumstances, and frequently 

 inappreciable by the chemist, of carbonic acid gas, ammonia, nitric 

 acid, and the effluvia arising from animal perspiration and the 

 decomposition of animal matter. On reaching the land, however, 

 its Solvent power immediately came into operation, and it became 

 impregnated more or less with the soluble substances with which 

 it came in contact; common salt and gypsum were always dissolved 

 by it, while lime and other substances were taken np by it when 

 tuere happened to be an excess of carbonic acid gas present. In 

 order to illustrate this fact, the Professor exhibited to the members 

 a simple and striking experiment. Three glass vessels were con- 

 nected together by means of bent glass tubes; the first vessel 

 contained fragments of marble (as a pure variety of native 

 carbonate of lime); the second, distilled water; and the third and 

 last, a clear solution of quick lime in pure water (or lime-water.) 

 On adding dilute muriatic acid gradually to the marble in the first 

 vessel, carbonic acid gas was disengaged in great abundance, which 

 passing along the tubing into the middle vessel, was there washed 

 and freed from inijuirity by its passage through the distilled water, 

 and then proceeded, by means of a connecting glass tube, to the 

 lower ])art of the inner surface, where it continued to bubble 

 throughout tlie clear lime-water. After a few moments the lime- 

 water became turbid. The Professor remarked, that this effect 

 resulted from the conversion of the lime into insoluble carbonate 

 of lime (or chalk), by its combination ivitb a first proportion of 

 the carbonic acid gas passed through it. In a few moments after- 

 wards, however, the liquid regained its original transparent 

 appearance. 'I'his change, he explained, arose from the further 

 supply of the same acid gas, constituting the insoluble carbonate 

 of lime a solulile super-carbonate of that earth; the liquid, in fact, 

 being then a solution, not of lime in water, as it was originally, 

 but a solution of bi-carbonate of lime, or of chalk rendered soluble 

 by excess of carbonic acid. To prove that this was the case, the 

 Professor took the flask containing this solution, and having placed 

 it over a spirit-lamp, caused ebullition to take place. .After boiling 

 for a short time, the liquid again became turbid, from the circum- 

 stance of the heat expelling the excess of carbonic acid, and again 

 reducing the carbonate of lime to the state of insoluble chalk. 

 He then proceeded to show how this experiment illustrated the 

 change which was found to take place in the waters of limestone 

 districts, which were naturally charged with carbonate as well as 

 the sulphate of lime; and also how it happened that, while water, 

 rendered hard by sulphate of lime only, did no injury to steam- 

 boilers, as that salt was not deposited on raising the water to a 



boiling temperature; hard water, on the contrary, holding a large 

 amount of carbonate of lime dissolved in it by carbonic acid, did 

 the greatest injury to them, by gradually depositing, on being 

 boiled, such cailxinate of lime at the bottom of the steam-boilers, 

 until it amounted to a hard calcareous incrustation. 



Hard Water. — Water was always rendered hard by holding ia 

 solution either tlie carbonate or the sulphate of lime; and, accord- 

 ingly, when obtained from wells in the chalk, oolitic, and limestone 

 districts througliout the kingdom, was always hard; becoming 

 turbid when boiled, and depositing its carbonate of lime on that 

 ])art of the internal surface of the boiler nearest to the fire. .\s a 

 familiar instance, he named the fur or crust in teakettles, in 

 districts where such water was used; but in the case of steam- 

 boilers, this deposit was one of the greatest evils that could be 

 imagined. The hard calcareous incrustation in immediate contact 

 with the iron plating of the boiler, amounting in a few weeks to no 

 less than from two to three inches in thickness. Professor \^'ay 

 explained Iiow the injury arose in this case — namely, from the effect 

 which the adhering crust had in preventing the transmission of the 

 heat, received by the boiler from the fire, to the body of water 

 within the boiler. He cited many curious instances of the cooling 

 effect of this free transmission of heat on substances under other 

 ciri umstances most fragile and combustible; and the contrary effect 

 when the transmission of such heat was obstructed, as in the case 

 of calcareous incrustation, w hen the heat was arrested by the solid 

 slow-conducting body, and the temperature raised above that of 

 boiling water. He stated that, however odd it might sound to 

 make the statement, it was no less true, that water might he boiled 

 in an orange-peel, in an egg-shell, or in a vessel made of thin wood, 

 or even of common writing paper; the heat applied to the external 

 surface being rapidly transmitted to the water, and the heat carried 

 off in the steam generated, while the material employed for the 

 boiler suffered no inj urious effect from such application of heat. 

 He related a singular instance of this kind, in the case of a person 

 at Liverpool, who had frequently had his cotton-mill burnt down. 

 The pai-ty in question imagined, that if he had a large reservoir 

 for water placed at the top of his factory, constructed of wood 

 instead of metal, the wood, in case of fire, would be immediately 

 burnt to ashes, and the water would consequently be set at liberty 

 and extinguish the fire. The fire unfortunately did break out 

 again, as it was feared it would, but the wood, instead of being 

 charred or burnt, remained entire, and, being encircled by the 

 flames, the water continued to boil in its wooden reservoir as long 

 as any remained. The furring of a boiler preventing this trans- 

 mission of heat, and thus causing injury to the substance of the 

 boiler, was the reason why, in some districts, where the w ater was 

 charged with bi-caibonate of lime, the boilers were found to wear 

 out sooner than in others; and why the railway companies had 

 been led either to seek for soft water, or to soften the hard water 

 they had been in the habit of using, by the addition of some 

 substance that w ould prevent its furring their boilers. The London 

 and South-Westcrn Railway Company had used the substance 

 known in commerce as sal-ammoniac, with great success; by 

 dissolving one ounce of it in 90 gallons of water, in tanks kept 

 specially for the purpose. This substance was the neutral salt, so 

 long familiar to chemists as the muriate of ammonia, being a com- 

 pound of muriatic acid and ammonia. Its action in removing 

 the hardness of water arising from bi-carbouate of lime was 

 explained by Professor Way in the following manner. \Vhen 

 muriate of ammonia and carbonate of lime are brought together 

 in solution, a double decomposition ensues, each of the four com- 

 bining substances changes its relative position, and two new salts 

 are the result — namely, carbonate of ammonia, w hicli is volatile, 

 and accordingly makes its escape into the atmosphere; and muriate 

 of lime, one of the most deliquescent salts with which chemists 

 are acquainted, and which consequently remains in the water in a 

 state of complete and almost permanent solubility. It might, he 

 remarked, be said, that the ammonia of the sal-ammoniac carried 

 off the carbonic acid, while the muriatic acid dissolved the lime, 

 thus liberating the water from the chemical conditions under 

 which its hardness was occasioned. 



Softening Water. — Professor Clark, of the University of Aber- 

 deen, had, however, proposed a plan for softening water rendered 

 hard by carbonate of lime, which Professor Way considered much 

 better than the one just described, and which might be adapted to 

 the uses of agriculturists. This plan consisted in adding to such 

 water a certain quantity of quick lime, which would unite with the 

 excess of carbonic acid, and become converted into carbonate of 

 lime, at the same time that it would reduce by such abstraction the 

 bi-carbonate also to a state of carbonate, and both being insoluble, 



