194 Prof. Schmidt on the Boracic Acid Fumaroles. 



the assertion of Payen, that the fumarole vapours, before their 

 passage through the waters of the lagoons, contain no boracic 

 acid, the following experiment was made. A large glass funnel 

 was fastened over one of the jets of vapour issuing from the 

 ground, and connected by means of a leaden pipe and several 

 long wide glass tubes with empty glass balloons, which served 

 as condensers. The gas evolved was a mixture of much carbonic 

 acid with a small quantity of sulphuretted hydrogen. Small 

 quantities only of nitrogen, and no oxygen were found. The 

 liquid condensed in the receiver reddened litmus paper, but ren- 

 dered turmeric paper brown ; and a quantity of it evaporated to 

 dryness and treated with sulphuric acid, imparted to the alcohol 

 flame the characteristic green colour of boracic acid, proving 

 that boracic acid exists preformed in the fumarole vapours. The 

 condensed liquid contained, besides, carbonic acid and ammonia 

 in considerable quantity. Distinctly estimable amounts of silica, 

 baryta, iron, alumina, lime and magnesia, were also found. From 

 a series of experiments, Schmidt supposes that the fumarole hquid 

 contains about O'l per cent, of boracic acid, and thinks that it 

 is in the form of borate of baryta. 



Hessel* found that by the addition of a certain quantity of cal- 

 cined gypsum to muddy wines, they were clarified and rendered 

 somewhat stronger, retaining their original taste and flavour. 

 Gypsum has the same effect on muddy beer, with the exception 

 that it is rendered more bitter. 



Two important methods for the artificial production of urea 

 are given by Natansonf. He shows that carbamide and urea are 

 identical. When carbonic aether is heated with excess of am- 

 monia in a closed tube to 100° C, urethane alone is formed ; 

 but if the temperature of the tube be raised to 180°, the boiling- 

 point of urethane, it is converted by the excess of ammonia into 

 urea. In the empty parts of the tube a sublimate of undecom- 

 posed urethane is deposited : the aqueous solution contains urea. 

 If this solution be evaporated to dryness and kept some time at 

 100° C, the urethane volatilizes and urea remains behind. 



In ] 838 Regnault obtained, by the action of phosgene gas on 

 ammonia, a white saline mass, which comported itself as a mix- 

 ture of carbamide and sal-ammoniac. In this mass urea must 

 probably have been contained ; but if the gases had not been 

 well dried, its quantity would have been small in comparison to 

 the other substances, and it might easily have escaped detection. 



Natanson prepared the phosgene gas by passing carbonic oxide 



* Liebig's Annalen, June, p. 334. t Ibid. p. 287* 



