Definition of "tungstic"

Having ſubjected to experiment an oxyd hitherto little known, I mean the tungſtic oxyd, I ſoon diſcovered that it is one of the moſt valuable ſubſtances for receiving and fixing vegetable colours.

1799, Cit. Guyton, “Experiments on the Colouring Matter of Vegetable Juices with the Tungstic Acid”, in Alexander Tilloch, editor, Philosophical Magazine, volume IV, number XIII, London: J. Davis, page 81

The tungſtic phoſoxyd (yellow oxyd of tungſten) appears to contain light in its compoſition. It gives out phoſoxygen, and becomes blue on expoſure to ſolar light. It appears capable of combining with the alkalies, alkaline earths, &c.

1799, Thomas Beddoes, Contributions to Physical and Mental Knowledge, Principally from the West of England, Bristol: Biggs & Cottle, page 120

Thoria is introduced as thorium nitrate into the tungstic oxide before the latter is reduced by hydrogen to tungsten power.

1924, Zay Jeffries, Robert Samuel Archer, The Science of Metals‎, McGraw–Hill, page 106