66 REPORT—1848. 
of oxygen without losing any hydrogen, for C,,H,O, + 30=C,H;O,. It — 
appears also that alizaric acid contains one equivalent of hydrogen less, and : 
three equivalents of oxygen more, than benzoic acid. ; y 
Pyro-alizaric Acid.—When alizaric acid is heated it is totally velatilized, — 
and forms a sublimate in the shape of long white needles, to which I have : 
given the name of pyro-alizaric acid. By the action of heat alizaric acid 
loses water, or the elements of water. Pyro-alizaric acid is soluble in boiling 
water. The solution, however, produces exactly the same reactions as alizaric 
acid itself, and on evaporation large rhombic crystals are obtained, which 
have quite the appearance of the latter acid. It is probable therefore that, 
by solution in water, pyro-alizaric, acid takes up again the elements of water, — 
and is reconverted into alizaric acid. The following results were obtained on 
analysing this acid: -- i 
I, 0°4405 grm. dried at 212° and burnt with chromate of lead, gave 1°0345 
carbonic acid and 0°1185 water. | 
If. 0°4255 germ. gave 0°9985 carbonic acid and 0°1215 water. | 
From these numbers it may be inferred that the composition is as follows:— 
Found. 
Calculated 
Numbers. t 7 
28 eqs. Carbon ...... 168 63°87 64°04 63°99 
, Sv Efydrogen ... 7 2°66 2°98 sips Wd 
11, Oxygen...... 88 33°47 32°98 32°84 
263 100°00 100°00 100°u0 
Hence it follows that by the action of heat two equivalents of alizaric acid — 
lose three equivalents of water, and give one equivalent of pyro-alizaric — 
acid, since 2(C,, H; O;) — 3HO = C,, H; On. i 
Rubiacin.—In my last report I described the method of preparation, and 
the properties of rubiacin and rubiacic acid, and I have nothing further to ~ 
add to wnat I there stated. 1 may mention however that I have arrived at © 
the conclusion that rubiacin cannot be considered as a true colouring matter, — 
as it is impossible to dye with it. I shall also show that, contrary to the — 
opinion which I was led to entertain in the first instance, rnbiacin does not 
contribute to produce any effect in the process of madder-dyeing. 
On subjecting rubiacate of potash and rubiacic acid to analysis, 1 ob- 
tained the following results :— 
I. 04490 grm. rubiacate of potash gave 0°1090 sulphate of potash, equi- — 
valent to 0°0589 potash. b 
0°4350 grm. gave 0°7950 carbonic acid and 0°0900 water. 4 
II. 0°3245 grm. gave 0°0790 sulphate of potash, equivalent to 0°0427 — 
potash. : 
0°2890 grm. gave 0°5315 carbonic acid and 0°0665 water. $ 
> 
From these numbers it may be inferred that the salt is composed as 
follows :-— ik vi 
Calculated 2 il rf 
Numbers. 7 ID Un 
81 eqs. Carbon.... 186 51°63 51°50 51°82 ‘ 
7 5  Hydrogen.. 7 1°94 2°29 B55 is 
15 ,, Oxygen .. 120 33°31 83:09 ° 32°47 ¥ 
rad sachet erg inf 13°12 ioke 13°16 4, 
560-27 10000 10000 10000 
: B 
.) 
