Mendeleeff endeavoured to obtain a connexion between surface energy and constitution; more successful were the investigations of Schiff, who found that the " molecular surface tension," which he defined as the surface tension divided by the weight.
Schiff, Ann., 1866, 140, p. 131).
Schiff, "Studien zur Geschichte Papst Nikolaus IV."
(1886-1893), and Otto Schiff deals with his pontificate in his Studien zur Geschichte Papst Nikolaus IV.
Schiff, Ann., 1896, 291, p. 367); and by the action of urethanes on urea chloride (L.
Klein also prepares a new prophylactic from the dried organs of a guinea-pig, and one of the most interesting experiments is that of Strong (Archiv far Schiff sand tropische Hygiene, April, 1906), who uses for producing immunity in man a living virulent culture of the bacillus pestis.
Jour., 18 93, 1 5, p. 198; 1894, 16, pp. 123, 154) has described PO(OH)2NH2 and PO(OH)(NH2)2, whilst the compound PO(OH)NH was obtained by Schiff (Ann., 1857, 103, p. 168) by acting with ammonia on the pentoxide.