"PETROL DOPES."

New Zealand Herald, Volume LXIV, Issue 19798, 19 November 1927, Page 12 (Supplement)

"PETROL DOPES."

TABLOID POWER. A warning was recently issued in these Columns concerning the elaborate claims Tvhich have been made for " dope elec-

'lrolytes." Auckland motorists might, With benefit, avoid another class of freak preparation—" petrol dopes." There are $ variety of these "sure-fire" and "money--oav*/ ' mijuures on tue market, bat, without Investigating their chemical content, fchey ivre bettor taken with a grain of Oalt than with a gallon of petrol. Just Cis " dope electrolytes" deluged in America, so did petrol savers follow in (great volume. The value of these tablets

Und powders must be obvious. Had the (preparations possessed any merit, the oil Companies would be only too keen to obOain patents for their exclusive use. tEvery large oil" refinery aims to obtain U reputation for producing a spirit which Tvill show economy in running in cold figures. What motorist would refuse a . ]petrol from which ho was certain of extracting two or three more miles per igallon! Many of these pellets and tablets are Hie subject of such lavish claims that no thinking motorist would be tempted to give them a trial. In the case of one preparation costing about 5s for a box of 12 pellets, it is recommended that one |>ellet should be added to every four gallons of petrol. It is claimed that the addition of this tablet, costing about Ed, will make four gallons give the mileage of six. The claim is too absurd to Interest anybody who cares to calculate the huge saving which is pronv'sed for use of a few grains of carbon, napthajine, and other cheap constituents. In Botrie cases these preparations are made for a few pence and sold for as many

shillings. It is sometimes claimed that the continued use of these dopes permits a reduction in the sizo of the carburetter jet. Alternatively the motorist is advised to fit a smaller jet before using the preparation. He naturally obtains an increased mileage. This he may attribute largely to the dope, forgetting that he has sacrificed considerable power and acceleration. The smaller jet suggestion is just a little deception which may result in an undeserved tribute to the dope. One of these tablet preparations, which has been extensively sold in England, h3s been analysed; The composition of tho tablet was: tino carbon. 3.84 per cent.;

heavy mineral oil, 26.52 per cent.; nap thnlino. 59.64 per cent.

These over-optimistic dopes should not be confused with chemicals which are intended to prevent knocking. Tetra-ethvl lead is being used extensively in America as an anti-knock accent. It has been accepted by reputable oil companies, and its use permits the employment of hirher compression ratios. The addition of tetraethyl lead is, however, a scientific matter better left to oil refinery.

PISTON SLAP. When some types of aluminium pistons ere fitted, they have to be provided with a generous clearance of the crown, owing to the fact that the aluminium alloy used expands more than cast-iron. As a result, when the engine is started from cold and has not attained its working temperature, the pistons tend to rock in the cylinders, thus giving rise to the noise known as piston slap. This knock is only experienced when the engine is cold or when running very slowly when warm.

ON A RUBBER PLANTATION. . Most people know that in the beginning motor tyres originate as a milky white liquid flowing from a tree. It is questionable whether the knowledge even of more than two in every hundred motorists goes further thau that. And yet these trees are tascinating One company has 55,000 acres of them in British Malaya, apart from reserve lands. From a distance the younger of these plantations look not unlike a string of English orchards. A small field of them was once a Government experimental station and some of thu trees, in this field were planted from seeds brought into the country by Sir Henry "VYickham almost half a century ago.

Spread over that considerable acreage is a staff of about a hundred Europeans and twelve thousand Asiatics—chiefly Southern Indians and Chinese. The Europeans are the organisers and supervisors. The rubber planter has no easy life; he is "on the go " from early morning, and often until late at night, nor is he too sure of unbroken sleep should one or two natives take it into meir heads to wake him up to settle some dispute—generally a domestic brawl of a trivial nature. About two-thirds of the coolies come from Southern India; the other four thousand are chiefly Chinese. Each of the coolies engaged on the actual " tapping " of the rubber is responsible for from three to four hundred trees. A careful watch has to be kept over these trees, if there be signs of disease instant steps must be taken to " doctor " them, and if one be cut down another is planted. Round a rubber tree is cut a spiral channel, and a metal spout is inserted at the bottom of this channel. Underneath the spout is placed a white porcelain cup. The rubber in the form of a liquid " latex " runs into this cup, and every day about noon the " tapping " coolies empty thoir cups into buckets and take the fluid to the estate factory. The rubber factories in Malaya are kept as clean as Sussex dairies. Here the rubber is poured into largo tanks and treated with different chemicals after ■which it is either smoked in a smoke house, somewhat resembling a Kentish hop drier, or turned into crepe rubber, in which case it is hung in drying rooms. The rubber is afterwards carefully sorted, packed and marked ready for shipment.