246 



HEATING AS APPLIED IN HORTICULTURE. 



Fig. 326. 



Fig. 327. 



Fig. 328. 



siphon may be removed from time to 

 time, by taking off the cap c at the lower 

 part of the bend." 



Pipes are connected in various ways ; 

 the following, however, are the principal, 

 — viz., the flange- 

 joint, fig. 325 ; the 

 spigot - and -faucet, 

 or socket-joint, fig. 

 326 ; the thimble- 

 joint, fig. 327 ; and 

 the saddle-joint, fig. 

 328. The flange- 

 joint is made by 

 placing some elastic 

 substance, such as 

 felt, pasteboard, 

 rope - yarn, caout- 

 chouc, well -satu- 

 rated with white- 

 lead and drying oil, 

 between the flanges, 

 and bringing them 

 firmly together by 

 means of three or 

 fourscrew-bolts and 

 nuts. This joint 

 presents a clumsy 

 appearance ; but it 

 has the advantage 

 of beingeasily taken 

 asunder, and hence 

 is valuable when pipes are laid down for 

 temporary purposes. 



The spigot-and-faucet, or socket-joint, 

 is the neatest and strongest, but can 

 scarcely be separated when once made, 

 unless joined with lead instead of rust, 

 which is found to make a secure and per- 

 manent joining. 



The composition generally used to 

 pack this joint with is called rust or 

 borings by tradesmen, and is a mixture 

 of iron borings with sulphur and sal- 

 ammoniac. The following are the pro- 

 portions given by Buchanan in " Essays," 

 p. 177 : — "To make iron cement, 40 

 parts by weight of iron borings are to 

 be added to 1 part of sal-ammoniac and 

 \ part of flowers of sulphur, well mixed 

 together, and beaten up like putty. 

 Much sulphur renders the composition 

 brittle. When a considerable time can 

 be allowed for the cement to dry in the 

 joint, before steam" or hot water " is 

 admitted into the pipe, a smaller propor- 

 tion of sulphur may be used." 



Mr Peckstone has given slightly dif- 

 ferent proportions in " Practical Treatise 

 on Gas- Lighting," p. 340. "The iron 

 borings are to be pounded in a mortar 

 until they are fine enough to pass through 

 a fine sieve ; then, with 1 lb. of these 

 borings, so prepared, mix 2 ounces of 

 sal-ammoniac in powder, and 1 ounce of 

 flowers of sulphur, by rubbing them well 

 together in a mortar ; afterwards keep 

 the mixture dry till it is wanted for use. 

 When it is to be used, for every part, by 

 measure, take 20 parts of iron borings, 

 prepared as prescribed, and mix the 

 whole well together in a mortar, and 

 bring the compound to a proper consis- 

 tence by pouring water gently over it as 

 it is mixing. It is then to be applied 

 between the flanges by a blunted caulk- 

 ing-iron, where it is to be well set up ; 

 and after the joints are screwed up very 

 tight, the loose cement is to be scraped 

 off." Of course the same mixture is 

 to be used for the other varieties of 

 joinings in the usual manner, and as else- 

 where described in this work. 



In joining hot-water pipes, rope-yarn 

 has often been used • but this, if much 

 saturated with tar, is objectionable, as the 

 tar melts with the heat, and consequently 

 the stuffing becomes loose and imperfect. 

 New or untarred yarn, or soft-spun rope, 

 is much better. In the case of flange- 

 joints, the same material was used, and 

 formed in shape of a collar ; now, thick 

 mill-board is preferred for this purpose. 

 Lead was used in the case of socket- 

 joints, and perhaps it is not much to be 

 objected to ; and when pipes are put up 

 for experiment or for temporary purposes, 

 it is certainly the best, as, when it is 

 necessary to take them to pieces, a fire 

 lighted under the joints melts the lead, 

 when the pipes, may be disengaged with- 

 out much trouble ; whereas, if permanent 

 joints be made of rust, almost no power 

 can take them asunder. 



Some engineers make the joints of their 

 pipes with iron filings, gold size, and lith- 

 arge. This, however, is not a good com- 

 pound, andhas been said to split the sockets 

 when the pipes become heated, — perhaps 

 from expansion in the two latter materials 

 being greater than in the first ; whereas 

 the expansion must always be only equal 

 to that of the pipes themselves. 



Messrs Cottam and Hallen make 



