Terra Ponderosa

In 1774, Scheele deterrnined that barium oxide was a distinct oxide or "earth," and named it terra ponderosa because of its high density (1). Later, this name was changed to barote from the Greek word meaning heavy. Later stUl, the name of the oxide was modified to baryta to conform to the nomenclature recommended by Lavoisier, and from this the name barium was derived... 

In 1783 he published an annotated translation of Torbem Bergman s Sciagraphia regni mineralis, and in the following year he communicated to the Philosophical Transactions his Experiments and observations on terra ponderosa (barium carbonate, or witherite) (96). He stated that the specimen he examined came from a lead mine at Alston Moor, on the Pennines of Cumberland. Although he at first mistook it for heavy spar (barite) he soon found it to be a compound of heavy earth (barium oxide) and fixed air (carbon dioxide) (97). 

In 1790 Dr. Adair Crawford (1748—1795) published a paper on The medicinal properties of the muriated barytes (barium chloride) (18). The muriated barytes exhibited in St. Thomas s Hospital since the month of May, 1789, said he, was obtained by the decomposition of the heavy spar. Having procured some specimens of a mineral which is sold at Strontean [sic], in Scotland under the denomination of aerated barytes, I was in hopes that the salt might be formed with less difficulty by immediately dissolving that substance in the muriatic acid. It appears, however, from the following facts, which have been verified by the experiments of my assistant, Mr. Cruikshank, as well as by my own, that this mineral really possesses different properties from the terra ponderosa [baryta] of Scheele and Bergman (49). 

Dr. Crawford showed in this paper that the salt (strontium chloride) obtained by dissolving the new mineral in hydrochloric acid differs in several respects from barium chloride. It is much more soluble in hot water than in cold, the strontium salt is much the more soluble in water and produces a greater cooling effect, and these two chlorides have different crystalline forms. He concluded therefore that the mineral which is sold at Strontean [sic] for aerated terra ponderosa possesses different qualities from that earth, although at the same time it must be admitted that in many particulars they have a very near resemblance to each other. He also stated that it is probable that the Scotch mineral is a new species of earth which has not hitherto been sufficiently examined and that Mr. Babington. . . has for some time entertained a suspicion that the Scotch mineral is not the true aerated terra ponderosa. In 1790 Dr. Crawford sent a specimen of the new mineral (strontianite, strontium carbonate) to Richard Kirwan for analysis (50, 66). 

Withering, W., Experiments and observations on terra ponderosa, Phil. 

In 1782 Withering, the famous Birmingham doctor who introduced the foxglove into medicine, discovered barium carbonate in the Leadhills, Scotland. This was called terra ponderosa aerata, but later the cumbersome appellation was altered to Witherite. ... 

Witherite (terra ponderosa aerata, barium carbonate) evolves fixed air when heated in a current of steam, and (as Priestley did not discover that hydrated baryta is formed) this shows that feed air consists of about half the weight of water . Hope found that feed air is evolved without the action of steam only at the temperature of a smith s forge. Priestley correctly found that lime water heated in a sealed tube deposited lime, which is less soluble in hot than in cold water. ... 

Barium carbonate, present in nature as terra ponderosa or witherite, was discovered in England and was described by William Withering, a colleague of Joseph Priestley. Scheele was the first to make clear the difference between barium and calcium (1774) and his achievement is quite on a par with Black s regarding magnesium oxide in 1755. In the latter case both Black and Davy are mentioned as the discoverers of the element, in the barium case Davy alone. Another inconsequence in the history of the elements. 

Barium Sulfates n (barites, blanc fixe, heavy spar, permanent white, terra ponderosa) BaS04. A white powder obtained from the mineral barite or synthesized chemically. One of the synthetic varieties, hlanc fixe, is made by mixing aqueous solutions containing sulfate and barium ions. As a filler in plastics and rubbers, barium sulfate imparts opacity to X rays but only a low order of optical opacity. Thus it is useful as a filler when it is desired to increase specific gravity without adversely affecting the tinctorial power of pigments. (Ash M, Ash I (1998) Handbook of fillers, extenders and dilutents. Synapse Informtion Resources, Inc., New York). 

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