1817.) during the Year 1816. 33 
posed of 100 metal + 5°5 oxygen. If this be a protoxide, as is 
probable, the weight of an atom of tantalum is 18. This oxide 
possesses acid properties. It is precipitated from its combination 
with potash by muriatic acid. (See Afhandlingar, iv. 253.) 
- 12. Manufacture of Glass.—Gehlen some time before his death 
was occupied with experiments on ‘the preparation of glass by 
means of sulphate of soda. Professor Schweigger has lately pub- 
lished the result of his trials. (Schweigger’s Journal, xv. 89.) He 
found that the following proportions were the best :— 
MBO «0.0. sia eyes caatsidie the bebidas aon Bti5 12 00 
Dry sulphate of soda ...... Pe ae Pia fair pO 
Dry quick-lime in powder ........ petiie os Zio, 20 
arcaal 16 <asntiiefein saa ih Br so of Sabai bing (1 
This mixture always gives a very good glass without any addition 
whatever. During the fusion the sulphuric acid is decornposed and 
driven off, and the soda unites with the silica. The sulphate of 
soda vitrifies very imperfectly when mixed alone with the silica. The 
vitrification succeeds better when quick-lime is added, and it suc- 
ceeds completely when the proportion of charcoal indicated in the 
formula is added ; because the sulphuric acid is thereby decomposed 
and dissipated. This decomposition may be either effected during 
the making of the glass, or before, at the pleasure of the workmen. 
XI. ACIDS. 
1. Oxalic Acid.—From the different analyses of oxalic acid 
which have been hitherto published, we may conclude that it con- 
tains twice as much oxygen in weight as of carbon, and that its 
hydrogen amounts to th of the whole. Dobereiner has made a 
remark which is entitled to some attention. (Schweigger’s Journal, 
xvi. 105.) The carbon and oxygen are precisely in the proportion 
which would result from the union of an atom of carbonic aeid with 
an atom of carbonic oxide. 
Carbon. Oxygen. Carb, Oxygen. 
Carbonic acid is composed of 1 atom + 2 atoms or 0:75 + 2 
Carbonic oxide .......... 1 a 075 + 1 
1°50 + 3 
When added together, we see that the weight of the oxygen is 
just double that of the carbon. Dulong says that when the oxalate 
of zinc or of lead is heated, it loses 20 per cent. of the weight of 
the acid; that afterwards, when the salt is exposed to a strong heat, 
no more water is driven off, but merely a mixture of carbonic acid 
and carbonic oxide, and that the metallic oxides remain behind in 
astate of purity. If we suppose oxalic acid to be composed of 
Oxygen ......... 3 atoms in weight 3 
CAIUON alec uhia'e op on Min iblbatenloty ena 15 
Hydrogen........ h a'aieen unmade 0 OF 
Vor. 1X, N° L Cc 
