NOTES AND QUERIES.

Otago Witness, Issue 3414, 20 August 1919, Page 39

NOTES AND QUERIES.

Qasttlons tor reply tn oomlns '»«»• *° *• "*" MiT«a aot UWr than SATURDAY night. QwMtioaa will WOT b* i»pliod to throws* «kt poai. * .' • Mineral, . Southland.—The green crystalline substance you sent for identification was submitted to Professor •■Bark, Dean of the. Mining' Faculty, -who has reported that it is the ferrous sulphate of iron usually called! copperas. It is a salt of iron readily soluble in water, and is of common occurrence in the roof of oaves, rock-sheltera, and in the underground -workings of old mines. The mineral' of commerce is artificially produced, since ferrous sulphate ia never found in Nature in sufficient quantity to be of economic value. A. T.—J"une 13, 1886, was the date of tho Maungatapu murders. Qtjbsto.—To obtain the information you require, you must -write to the secretary l of the Public Service Commissioners. Everything is centralised in Wellington' nowadays, and local-officials are rarely in a position to give any details. Inquirer.—(l) Ferrets breed twice a year. (2) It is diffioult testate definitely, but from three weeks to a month elapses before the young have their eyes open. Concrete. —'Mr H. M. Davey, consulting) engineer, replies:—"No one seems to know of what can be done with the substance you mention, andl apparently this eesjms to be that usually it is not readily obtainable in any considerable quantity to warrant experiments with it. From your questionit is not known as to whether you intend the substance to be used entirely by itself in place of the usual cement cr lime, adding sand, or whether you intend it to form *> What is called the aggregate, adding cement; but probably it may be the former. Tie only thing for you to do would be to experiment with it, making _ cakes of similar size and shap-p with various mixtures, possibly also some of them with the addition of a little lime or cement, and see which. Is the best mixture. You may then find out exactly what it is good! for, andi let the editor know, the result of the experiment, which will be instructive to others as well as yourself." Farmeb, Southland.—Mr H. M. Davey replies:—"The information you send is not quite sufficient to calculate the orea from, as the plan seems to contradict itself; thus, the straight line marked X> in the eketeh the editor is sending you is stated to be longer than the doubles lines marked A and B, though in the plan these two lines seem much longer than the single one. Now, if the three sides marked on the plan sent 0, D> and B are correct, what you have to. do is to give the length of A, end also of B, and the angles marked! F and G. If you do not know the way to give the angles correctly, you will see a good way on the other leaf of the paper sent. Measure, say, one chain on either side and then across from the places the chain measurements came to; then, if the measurements are correct, a correct area can be calculated for you."