Silicate adulteration

Butter is adulterated principally with oleomargarine 1 and less frequently with other animal or vegetable fats (tallow, cacao-butter, cottonseed steariiu-, oils) sometimes considerable quantities of water are incorporated wit h it and preservatives (ordinary salt, borax or boric acid, salicylic acid, formalin, fluorides or fluoborates, etc.) or colouring matters added very rare are such coarse adulterations as gypsum, chalk, flour, glucose, sodium silicate-, etc. 

The name Iron minium is given to a product composed essentially of ferric oxide mixed with day and sometimes also with siliceous sand and forming a fine, heavy powder of a deep red colour this also may be adulterated with gypsum or chalk and may contain admixed organic colouring matter. 

This is a complex compound of aluminium and sodium silicate and sodium sulphide. The typical and most common ultramarine is blue ultramarine, which forms a very fine powder (microscopically crystalline) of a pure blue, reddish blue or greenish blue colour according to the proportions of the components and the method of preparation ultramarines of other tints, especially green and violet ultramarines, are also made. Ultra-marine may be adulterated with gypsum, chalk, clay, heavy spar, zinc white and magnesium carbonate and may also be mixed with glycerine and glucose. 

Salter mentions that red lead was frequently adulterated with earthy substances, such as brickdust, red ochre, and colcothar . Various additives are also mentioned by Toch, including silica, lampblack, graphite qq.v.) and silicate of alumina. Conversely, this compound has not infrequently been used to adulterate vermilion q.v. Gettens et al., 1993b). 

Calamine was originally a native basic zinc carbonate containing iron and siliceous matter, but it is now almost entirely manufactured from precipitated zinc carbonate and zinc oxide. For a complete analysis, the loss at 105°, residue on ignition, carbon dioxide, hydrochloric acid-insoluble matter, iron, and total zinc by ferrocyanide titration should be determined. Calcium carbonate is a common adulterant, magnesium carbonate and oxide have also been found in place of the zinc. 

---