MISCELLANY OF NOTES AND CORRESPONDENCE. 91 



On Heating Apparatus bx means of Hot Water, &c. — In a recent number 

 of the Gardeners' Chronicle, Mr. Lindley has made some useful remarks on a 

 subject of much importance to gardeners relative to the apparatus of heating 

 plant houses, &c, by means of hot water. We extract the following. " The 

 most serious objection that has been made to hot water as a heating medium, is 

 its tendency to incrust the interior of the apparatus with carbonate of lime, thus 

 producing explosions, or rendering the fire inefficient. We have now before us 

 an instance of the kind where a boiler became lined, in a few months, with a 

 crust nearly half an inch thick, and as hard as freestone ; and there is no 

 doubt that such deposits are accumulating in all hot water boilers and tanks, 

 with more or less rapidity, according to the impurity of the water employed. 

 Indeed, every one who has a hot-water apparatus in action must, unless he con- 

 stantly uses rain water, expect to be obliged seme day to pull it down for the 

 purpose of having it cleaned. 



" This inconvenience is more serious than is commonly supposed, and having 

 been found universal in steam boilers, has attracted the attention of Dr. Ritter- 

 brandt, who lately brought the subject before the Society of Arts, suggesting an 

 effectual cure. 



" In order to obviate the difficulties just spoken of, Dr. Ritterbrandt proposes 

 to use the salts of ammonia, it being known that if to a soluble salt of lime be 

 added a solution of carbamate of ammonia, precipitation takes place, and the 

 acid which held in solution the lime unites with the ammonia, while the car- 

 bonic acid of the carbonate of ammonia combines and falls down with the lime ; 

 but, upon the water being heated, the precipitated carbonate of lime combines 

 with the salt of ammonia, is redissolved, and the carbonate of ammonia is 

 formed and escapes with the vapours of the boiling water. Feeling convinced 

 that this peculiar reaction took place, viz., that carbonate of lime, precipitated 

 from a salt of lime by carbonate of ammonia, would be again dissolved by the 

 application of heat, it only remained to be proved how far the principle was 

 capable of decomposing the carbonate of lime already existing in calcareous 

 water, and the results exceeded the most sanguine expectations. However 

 highly charged with lime water maybe, the process answers, and the solution 

 is in all cases perfect. 



•• Mr. Gooch, of the Southampton Railway, stated that when the subject first 

 came under his consideration, there were two points which he was desirous of 

 having made clear to him. The first was— that the ammonia did actually pre- 

 vent the deposit ; and the second, that the application of the muriate when 

 applied to cleanse boilers did not produce any injurious effect upon the metal. 

 Upon both of these points he expressed himself perfectly satisfied, and stated 

 that he bad adopted the plan with all the engines under his superintendence. 

 Tne quantity of ammonia used on the Southampton Railway is at the rate of 

 one pound for every 1500 or 2000 gallons of water. The cost of the ammonia is 

 about 3d. per pound. Mr. Goodiff had also seen experiments made on the 

 engines of steam vessels, one of which, George the Fourth, had its boiler com- 

 pletely incrusted ; but after the experiment had been carried on for six weeks, 

 the boilers became clean. It had also been tried in a small stationary high- 

 pressure engine, of eight horse power, working with salt water, and the same 

 results followed. 



" The lesson which gardeners should learn from this important practical 

 communication is, that if they wish to keep a hot-water apparatus in working 

 order, without running the risk of the interior becoming ' furred' up, they will 

 invariably add one ounce of sal ammoniac (or muriate of ammonia) to every 

 ninety gallons of water with which their apparatus is filled." 



Campanula Pyuamidalis.— It being the season of the year to promote the 

 growth of this splendid flowering old plant, Ijust direct the attention of your readers 

 to try it, by having some in pots, promoting their growth in a close frame — a 

 coulish one, till they can be grown there, then remove to a greenhouse till the 

 plants are about to show the flower, then let a portion of them be kept in the 

 light of a north-aspected window, and. the flowers then instead of being blue, 



