rKESII)i:XTIAL AUI)Ki:SS — SliCTJON A. 



63 



liccn [he main fuel in tlie pasi. "fSTt now all 'litficultics in the way 

 ui utilising lar oils haxc bci'Ti ovorconie. Unfortunately, the 

 price of tar has hocn inorease<i throuij^h its extensive use for 

 spraying roads. .At a recent meeting ( I'ehruar}'. i<)i6) of tlie 

 Diesel I'Jigine Users' Association, ii was stated that of the 

 850,000 h.p. develoi)e(l in Uicrmany t)y Diesel engines, 150.000 

 h.p. was ])rodticed from tar or tar oils. Iveniernhering', also, how 

 essential tar is for chemical manufactures, it will be recognised 

 how important it i^ that the (lcj)l(iral)lc waste of coal should be 

 stopped. 



.\rrangements have recenth- l>een made for the storage of 

 fuel (m1 at the i)rincipal South .\irican ports, the price being 

 in the neighbourhood <if ih 10^. per ton. .\t the present time, 

 this high cost of oil renders the use (U' the Diesel engine jtrac- 



Fk;. 39. — High Compres.sion or " Seini-I )ifSLl "' ( )il F.ngine of 35 15.1 1-P. 

 for Crude or Residual Oils. 



tically prohibitive up-country, excejn as a stand-bye : it is in 

 regtilar use at coast towns, where coal is expensive, and at a 

 lew places to which the cost of railway trans])ort is not too high. 

 A source of hx^ally-made tar-oils would he a matter of great 

 im])ortancc. Within the ])ast few year< a cheaper engine, 

 known as the Semi-Diesel or " lUilh " engine, an examjjle of 

 which is shown in Fig. ^tj. has been de\'i.>ed for burning heavy 

 oils: it is practically a hi.gh com]>ressiiin jiarattin engine, with 

 compression of air alone on the Diesel principle to about 2J^ lb-. 

 l)ressure. 



The best constimptions max be taken as approximatelv ; 



Diesel engine with heav}- i)etroleum oils: .4 to .45 lbs. per 

 b.h.]). ])er hotir. 



Diesel engine with tar oils: .43 to .47 lbs. per b.h. p. per 

 hour. 



Semi-Diesel engin.e with hea\v |ietrol.-um oils: ab'iut .5'h. 

 per b.h. p. i)er hotu'. 



