ryifl 36. a n't tin in ton Dfon fingcmauerte* jupc 



.via redd 



Kill! 



man 



Moil 

 i^oc- 



Ulvn 

 ncm 



Figure 4. — Apparatus for converting white phos- 

 phorus into the red allotropic form. 1851. Redistilled 

 phosphorus is heated in the glass or porcelain vessel (g) 

 which is surrounded by a sandbath (e) and a metal 

 bath (b). Vessel (j) is filled with mercury and water; 

 together with valve (k), it serves as a safety device. The 

 alcohol lamp (1) keeps the tube warm against clogging 

 by solidified vapors. Because of hydrogen phosphides, 

 the operation, carried out at 260 C, had to be watched 

 very carefully. (According to Arthur Albright. 1851; 

 reproduced from Hugo Fleck, Die Fabrikation chemischet 

 Produkte . . . , page 112.) 



production of phosphorus for matches, the workers 

 experienced the poisonous effects. In the plant of 

 Black and Bell at Stratford, this was prevented by 

 inhaling turpentine. Experiments on dogs were car- 

 ried out to show that poisoning by phosphorus could 

 be remedied through oil of turpentine. 18 



Chemical Constitution of Phosphoric Acids 



In a long article on phosphorus, Edmond Wilhu 

 wrote in 1876: ''For a century, urine was the only 

 source from which phosphorus was obtained. After 

 Gahn, in 1769, recognized the presence of phosphoric 

 acid in bones, Scheele indicated the procedure for 

 making phosphorus from them." |,J Actually, Gahn 



used at first hartshorn (Cornu cervi usliim), and Scheele 

 doubted, until he checked it himself, that his esteemed 

 friend was right. A few years later, Scheele corrected 

 Gahn's assumption that the sal microcosmicum was an 

 ammonia salt; instead, it is "a tertiary neutral salt, 

 consisting of alkali minerali fixo (i.e., sodium), alkali 

 volutin, and acido phosphor 7." 20 



In the years after 1770, phosphorus was discovered 

 in bones and many other parts of various animals. 

 Treatment with sulfuric acid decomposed these ma- 

 terials into a solid residue and dissolved phosphoric 

 acid. Many salts of this acid were produced in 

 crystalline form. Heat resistance had been considered 

 one of the outstanding characteristics of phosphoric 

 acid. Now, however, in the processes of drying and 

 heating certain phosphates, it became clear that three 

 kinds of phosphoric acids could be produced: ortho, 

 pyro, and meta. 



Berzelius cited these acids as examples of compounds 

 which are isomeric. This word was intended to 

 designate compounds which contain the same number 

 of atoms of the same elements but combined in 

 different manners, thereby explaining their different 

 chemical properties and crystal forms. It was in 1830 

 that Berzelius propounded this companion of the con- 

 cept, isomorphism, which was to collect all cases of 

 equal crystal form in compounds in which equal 

 numbers of atoms of different elements are put 

 together in the same manner. Together, the two 

 concepts of isomerism and isomorphism seemed to 

 cover all the known exceptions from the simplest 

 assumption as to specificity and chemical composition. 



However, only a few years later Thomas Graham 

 (1805-1869) proved that the three phosphoric acids 

 are not isomeric. He used the proportion of 2 P to 

 5 O in the oxide which Berzelius had thought justified 

 at least until "an example of the contrary could be 

 sufficiently established." 21 Refining the techniques 

 of Gay-Lussac (1816) and several other investigators, 

 Graham characterized the three phosphoric acids as 

 "a terphosphate, a biphosphate, and phosphate of 

 water." Actually, this was the wrong terminology for 

 what he meant and formulated as trihydrate, bi- 

 hvdrate, and monohydrate of phosphorus oxide. In 



ndu v 



P., .is (IHi.'il, vol. I,!!, 



18 J. I'l 1: SI INN) , ( ompti f-l 



pp. 543-546. 



l » A. Wurtz, Dictionnaire d ' ■ (Paris, 1876), vol. 2, part 

 2, p. 951. 



-"Karl \V. Scuiili:, .Xmli ■;■■'■•■ Ihufc mid Aufziii/i'imigen, 

 edit. A. E. Nordenskiold (Stockholm: Norstedt, 1892), pp. 38, 

 144. 



:1 J. J. Berzelius, Lehrbuch, transl. I'. W6hler (Dresden, 

 1827), vol. 1, part I, p. 96. 



182 



BULLETIN 240: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



