Ohinemuri Regional History Journal 3, April 1965
By G. Chappell
The Refinery, situated in Willoughby St. between the main street and the Recreation Ground was built about 1912 by the National Bank of New Zealand to refine Bullion bought from the Waihi Grand Junction and the Talisman Mine at Karangahake, as well as from several smaller Mines, including some at Komata, Puriri, Thames Coromandel and Te Aroha. It was then under the supervision of Mr. Frank Budd with Mr. Len Bell as Assayer and Chemist. The pure refined gold and silver was sent sometimes to the Melbourne Mint and sometimes to America. Later the Grand Junction erected its own Refinery, as the Martha Gold Mining Company had done, and this left the Talisman and small Mines to supply the Refinery in Paeroa.
When the First World War started no Bullion was sent overseas at all, but was bought by the British Government and stored in Wellington. This of course included all that produced in the South Island as well. At the end of the War all of this Bullion was sent up to Paeroa under armed escort to be refined and sent back to Wellington, as pure Gold and Silver, finally to be sent overseas to the Royal Mint in England. It was during this time, after returning from the War, that I was employed at the Paeroa Refinery by the National Bank of New Zealand.
At times we had as much as half a million pounds worth of Bullion in the strong room. It would have made a nice haul for thieves had they been able to get away with it, but thank goodness we had nothing of that sort, although we did have a couple of false alarms. There were three bedrooms in the Refinery and two of the Bank Staff and I slept there. It was a strict rule that at all times at least one of us must be on the premises.
The inside of the main building was lined with very fine corrugated iron and the windows were about l6 feet up. Two of the staff were away at a dance one very stormy night when there were high winds and heavy rain. I went to bed as usual but was awakened by an awful row as though somebody had got through one of the windows and was sliding down the wall on a rope with the toes of his boots rasping down the corrugations. Jumping out of bed with my gun in my hand I stealthily went out into the passage and had a look through the peep shutter into the main building which was always lighted. I waited some time but could see nothing so I plucked up courage, got my keys and opened the main door. I had a good look round without seeing anyone, but nearly fell over the window pole lying on the floor. It usually stood up against the wall near the windows and the vibration set up by the wind must have caused it to slide down the corrugations, its brass hook making that fearsome noise in the middle of the night.
The second, occasion was also when the other two were away for the night, and this time I was awakened about 2 a.m. by what sounded like someone trying to get into the strong room. I lay and listened and was sure I heard somebody moving about. The private rooms I may state, were lit by Gas, and a pilot light was always kept burning. Such a light was fitted to the wall at the head of my bed. I fancied I heard someone entering my room, so taking my revolver from under my pillow I gradually sat up in bed. As I did so a head at the foot of the bed rose also. I waited no longer but let drive and shot the poor devil between the eyes. Then jumping out of bed I turned the lights full on, but could find no corpse. What I did find was a shattered mirror on my dressing table at the other side of the room. Alas for imagination! What I had seen as I slowly sat up was my own head rising over the foot of the bed - but it was in the mirror. The real burglar turned out to be a cat that had been locked in the bathroom and was trying to get out.
THE REFINING OF GOLD AND SILVER
The gold, silver and other metals were dissolved by cyanide solutions and precipitated into metallic zinc shavings in the form of a black slime. At the Refinery the slime was treated with sulphuric acid to dissolve the surplus zinc contained therein. The slime was now washed in hot water, dried in a large furnace and melted with borax, soda and sand in an oil-burning furnace. The resulting Bullion, which was alloy of gold, silver, copper, lead, iron and other metals, was bailed out into moulds, each bar weighing 1,000 ounces. This was the first stage of refining.
The bullion was now conveyed to a large cupel furnace where as much as 25,000 ounces were melted at one time. In this furnace a large percentage of the metals, other than gold and silver, were oxidised off with the aid of added lead, the process reducing the base metal down to about 2 per cent. From here the bullion went to the silver coils, so called because it was here that the silver was separated from the gold, by the aid of nitric acid and an electric current. During this process the silver was dissolved and precipitated in the form of pure silver crystals which were washed in boiling water, dried and melted into 1,000 ounce bars ready to be shipped away.
The gold from the silver cells was now collected, washed and melted into slabs and then put into the gold cells. Here by electrolysis the gold was dissolved and re-deposited as chemically pure gold on strips of pure gold foil hung in the cells. When this process was finished the deposited gold was collected, washed in boiling water, dried and melted and cast into 400 ounce bars, worth about £5,000 each. These bars were packed into specially made boxes and sent to the Mint.
Before being sent away, the gold and silver had to be assayed. In the case of gold a sample was taken either by chipping a piece off the ends of the bars, or by boring a hole right through. A small quantity (about 10 grains) of the sample was now weighed out on very sensitive scales, capable of weighing down to one thousandth of a grain. It was wrapped in a small piece of sheet lead, together with about 2½ times its weight of silver. This package was now placed in a small cupel made of Morganite and thence placed in a cupel furnace, the cupel absorbing the lead and any impurity contained in the gold. When the process was finished all that remained on the cupel was a small button of gold and silver. This button was flattened out on a small anvil and then rolled into a strip about two to two-and-a-half inches long in am small rolling mill. The strip was then rolled round a small piece of glass rod, put into a flask of boiling nitric acid, which dissolved the silver and left the gold in a pure state. It was then washed in distilled water, dried and weighed and the value of the gold calculated at so much per ounce. In the case of the silver the value was obtained by a chemical analysis.
MR. CYRIL GWILLIAM is well known as the elder son of the late "Old Ben", in whose footsteps he has followed so far as knowledge of our district is concerned. He was born at Karangahake in 1900, had his early schooling at Waitekauri and Sec. at Paeroa. Later taught, - 5 years Overseas Service. Throughout his life has been great Church Worker - Organist, Lay Reader. His services greatly missed in Paeroa when last year he retired to Tauranga where he and his wife are still very active and where his nearly 90 year old Mother lives with his sister. He is an invaluable member of our Hist. Society, his chief hobby being delving into the past, tramping the old haunts and writing reminiscences.
MR. GEORGE CHAPPELL who has contributed articles to each of our Journals, is the only mining "Official" left in Waihi to-day, having spent 35 years as Chief Assayer at the Martha Coy's Refinery. He is a veteran who has proved invaluable to us.
MR. C. W. VENNELL has been a Journalist (Aust. and N.Z.) for over 40 years and twice has been awarded the Cowan Prize for historical writing. He wrote the centennial history of Cambridge in 1939 and was part author of the "History of the Matamata Plains" in 1951. Having spent some years in the Bay of Plenty, he has been closely associated with the Tauranga Society, of which he is a life member, and also a member of the Elms Trust. Since joining the staff of the New Zealand Herald he has contributed many historical articles to that paper and to the Weekly News.