522 



NATURE 



[January 6, 191 6 



IPfi 



■f"''i«lii,,.i ' 



MODERN SYSTEMS OF INDEPENDENT 

 LIGHTING AND HEATING. 



(i) Oil, Oil Gas, and Petrol-air Gas Systems. 



UNTIL quite a late period in the nineteenth 

 century country houses were invariably lighted 

 either by candles or oil lamps. To-day there are at 

 our disposal many different systems of lighting, suited 

 respectively to the cottage and the mansion. 



For small houses in remote districts there is still 

 a good deal to be said for the paraffin or petroleum 

 lamp, provided a well-constructed and trustworthy 

 type is employed, and the oil used is of a good 

 standard quality. At the present time lamps giving 

 as much as loo candle-power can be obtained, and in 

 favourable circumstances 300-500 candle-power hours, 

 or even more, can be obtained per gallon of oil. The 

 fact that the oil lamp is entirely self-contained and 

 can readily be moved from place to place is naturally 

 an advantage, and the low intrinsic brilliancy of the 

 flame and the mellow colour of the 

 light are considered pleasing by 

 many people. 



The type of shade used with the 

 oil lamp is of some importance. 

 The vertical shallow tin reflectors 

 attached to cheap forms of parafiin 

 lamps are not very satisfactory. 

 Such lamps are sometimes hung on 

 the walls, throwing out the light 

 into the .room indiscriminately and 

 giving a somewhat glaring effect. 

 It is preferable to use some form of 

 diffusing glass shade completely 

 screening the light from the eyes 

 and directing the rays downward to 

 the table. The oil lamp is probably 

 at its best when equipped with such 

 a shade, and used in a central posi- 

 tion in the room, or immediately 

 above the surface it is intended to 

 illuminate. 



The introduction of incandescent 

 oil lamps (i.e. lamps using oil or 

 paraffin vapour with an incandescent 

 mantle) led to a great increase in 

 efficiency. There are now many 

 such lamps on the market. For ex- 

 ample, the Petrollte lamp, in which 

 air is sucked through a porous 

 material impregnated with suitable 

 hydrocarbons, a draught being 

 secured by using an exceptionally 

 long chimney. The lamp is claimed 

 to be exceptionally safe, as it goes out at once if 

 accidentally upset. According to some recent tests a 

 light of 40 candles can be obtained by burning i^ oz. 

 of hydrocarbon per hour. 



The incandescent oil system, however, gives the 

 most efficient results when used for relatively power- 

 ful lighting units. A well-known type is the 

 Blanchard lamp, using paraffin vapour, with an in- 

 verted mantle. These lamps range in illuminating 

 power from 100 to 1500 candles, and are claimed to 

 give more than 10,000 candle-hours per gallon of 

 oil. Their use is very simple, and the evolution of 

 vapour can be easily started with a little spirit. 

 Amongst other lamps of this type we may mention 

 the Kitson, Still, and Petromax lamps, all of which 

 are capable of giving a high candle-power, and are 

 particularly useful for lighting large rooms, country 

 halls, yards, etc., or for f§tes and garden parties. 



The illuminants mentioned above are all self-con- 

 tained and portable, and are cheap and simple in 



NO. 2410, VOL. 96] 



Fig. I.— "Petrolite" 

 lamp using upright 

 incandescent mantle 

 fed by air which 

 has passed through 

 porous material im- 

 pregnated with vola- 

 tile hydrocarbons. 



operation. On the other hand, they naturally require 

 a little attention, so that in larger residences the 

 trouble involved in looking after a large number of 

 lamps in different rooms 'is worth consideration. 

 Hence there has sprung up a demand for a distribut- 

 ing system, similar to gas and electricity, and avail- 

 able in localities where these methods of lighting are 

 not available. The "petrol-air gas plants," of which 

 there are now a number of types on the market, were 

 designed to satisfy this need. 



Petrol-air gas consists simply of air to which has 

 been added a small percentage of petrol vapour. Such 

 a mixture is very easily produced owing to the volatile 

 nature of petrol, and can be generated by a small 

 automatic plant, conveniently kept in a small out- 

 house. The mixture generated is then led into the 

 house through pipes and distributed to incandescent 



Fig. 2.— Types of small candle-power portable Blanchard incandescent 

 oil lamps. With this system units fiora loo to 1500 c.p. can be 

 obtaiiieo. 



burners in the same way as coal-gas. (This gas can 

 only be used with mantles, and is not suitable for 

 burning in flat flame burners.) The percentage of 

 petrol employed is invariably small (2-6 per cent., 

 according to the system). The gas has only a slight 

 and not unpleasant smell. Owing to the large amount 

 of air carried into the burner through the pipes the 

 vitiation of the air is small, and, as there should be 

 no objectionable impurities, the system is also clean 

 and hygienic. In view of the small amount of petrol 

 vapour^ used, the system is also claimed to be safe, 

 and it is said that even a leak would not, in ordinary 

 circumstances, give rise to any danger of fire or ex- 

 plosion. It is, however, essential that the consumer 

 should purchase a trustworthy tj'pe of machine. In 

 some of the earlier plants the composition of the 

 mixture was apt to vary according to the load and 



