MEDLEY OF TESTS

Dominion, Volume 25, Issue 264, 3 August 1932, Page 8

MEDLEY OF TESTS

Dominion Analyst’s Work MILK, GOLD AND GAS Some Remarkable Methods Had anyone visited a certain part of the South Karori stream yesterday he would have beheld the unusual sight of two men bottling a small quantity of water. Gravely and with care they sealed the containers, afterward returning to the city whence they came. An hour or so later the men were to be seen pouring the bottled water into glass tubes, heating it, gazing at it through microscopes. These proceedings took place at the laboratories of the Dominion Analyst in Sydney Street. Yesterday’s test of the South Karori water is only one of the multitude of tasks undertaken by the laboratory staff. On behalf of the Government they examine samples of almost every conceivable substance used and usable in the dally life of the community. About milk and printer’s ink, coal gas and eel soup they issue exceedingly blunt but strictly confidential reports. An idea exists that the Dominion Analyst and his score of skilled assistants are simply guardians of public health who occasionally, help to bring criminals to Justice by examining gruesome exhibits collected by the police. The truth is that, while the analysts are forever examining and checking the foods and drinks consumed by New Zealanders, they are equally active in protecting the State purse. Bad Ink and Bitumen. If bad ink be supplied to post offices, and pens clog and splutter, the Dominion Analyst will investigate. One of his departments will test the ink chemically until the constituent that Is causing the damage has been located and identified. Thus a waste of post office pens and stationery will be eliminated. When the season for road repair work and bituminising reaches its height another of the Dominion Analyst’s many laboratories —a department equipped specially for roading investigation—will grow increasingly busy. Bitumen and tar will be analysed in strange, twisting flasks and retorts. Samples of cement will be shaken through a series of sieves, one of which is so fine that in every square inch of mesh there are nearly 40,000 tiny holes. The increased activity in gold-bearing districts has resulted In much extra work for the analysts. Samples of quartz thought to contain gold and other valuable minerals are reaching the laboratories in large numbers, and each is carefully treated and reported upon. Scrap of Paper Weighed. “The balance room is the heart of the laboratory,” said a member of the staff as he ushered a “Dominion” reporter into a quiet room. Against each wail were benches, on which were several “balances,” each In its dustproof glass case. Taking a piece of notepaper no larger than a halfpenny, the analyst placed it on one of the pans of the balance. The pan descended with a thud. A weight consisting of a minute fragment of wire was adjusted. “The paper weighs .0276 of a gramme,” said the analyst, peeping at the scale through a telescopic eyepiece. There is one instrument in the balance room so delicate that the. maximum weight it can be called upon to weigh is half a gramme. It is used for weighing samples of gold. Another instrument is actually cushioned on air in such a way that the time-wasting swinging of the balance is avoided.. Upstairs in a special laboratory is a man who reduces rock to liquid." Engaged largely on analytical work associated with geological surveys, he tests samples from all parts of the country, determining to an exact degree their component parts. . Bubbling in a test tube on his bench was a small quantity of what might have been limejuice. In reality it was granite. The. analyst is a man of parts. One room in the building houses an apparatus to determine the melting point of ash. It seems that this singular piece of information is required because ash that “melts” or forms hard clinkers at a comparatively low temperature is apt to cling to firebars and lessen the efficiency of furnaces. Bottles of Fire Damp. Next door is a little room in which mine air is. being tested for “fire damp.” The samples of air are brought in bottles from various New Zealand mines and .treated in a piece of apparatus, consisting chiefly of glassware, and complicated enough to resemble a set of mechanical intestines. “How is the air got into the bottle?” He eyed his questioner pityingly. “Well, you just fill the bottle with mercury, take it to a certain part of the mine, empty it, seal it up, and there you are.” “There you are” is probably the easiest way of describing quite a number of the features of the Dominion laboratories. For instance, there is the “spectroscope” which determines by colour the presence of certain substances in a given sample. There is the colorimeter which fixes the depth of colour in cases where the result of the analysis is dependent upon this information. There is an ultra-violet ray lamp which is exceedingly useful in catching forgers. Rancid Butter and Bananas. In another room a machine like the “ticker-tape” of a Wall Street stockbroker’s office keeps an efficient-looking brass finger on the pulse of Wellington’s gas supply. Pressure and heating value are both recorded on the “tape” which curls slowly into a basket. Behind another door a man is investigating the problem of rancidity in butter. In some mysterious way he has transformed the rancid butter at his disposal Into a pink liquid. He is gazing at the liquid through a colorimeter. Beside him is a large wooden box, recently used for the storage and ripening of bananas under conditions exactly the same as those encountered during a banana’s' journey from an island tree to a city shop. There is a room. for the analysis of fuel and lubricating oils, a room for the testing of coal. There is a department wherein samples of the city milk supply are tested at frequent intervals, and another where the purity of the city’s water is checked. There is a large cabinet filled almost completely with samples of clay from various parts of New Zealand —clay which has been fired to determine its suitability for brick-making. The testing of kauri gum for the purpose of finding new and better ways ot treating and marketing it is another job that keeps Bunsen burners glowing, strange liquids bubbling, and queer odours mingling In the laboratories of the Dominion Analyst