140 
REPORT- 1847- 
lately, that I have not yet been able to ascertain its composition and atcuu 
weight. 
Alizaric acid .—At one period of my investigation I imagined thatalioni 
and rubiacin might be separated by boiling the mixture n-ith pcrchloriifc -f 
iron, in which case I cxpecteil the rubiacin to dissolve in the solution ofik 
iron salt and the alizarin to remain behind io eomhination with oxide of int 
I was not aware at that time that alizarin is decompose! by perchloriife 
iron. Before 1 had di.scovurotl this, however, I had taken about one liuadm 
weight of madder, treated it M’ith boiling water, added acid lu the fluid, 
rated the brown precipitate by filtration, and treated the whole quantitrri 
precipitate with porchloride of iron. The fluid was, after the adciitioc 
acid and filtration, evaporated to a syrup. After allowing the syrup tojaal 
for some days, I found it filled with white cry.stals heariup a resemblanw^ 
oxalic acid. I added water to the syrup, filtered and washed until tfw »»• 
chloride of iron was removed. I found that the crystals bore wasliiopviu 
cold water without dissolving in any considerable degree. I then dissoW 
them ill hot caustic alkali, filtered to separate some oxide of iron wbicli 
mained behind, and added sulphuric acid to the fluid while still hot Ontk 
fluid cooling there separated a quantity of long shining white crysiab.'lii'i 
were separated by filtration and washed. I now found that they conBiw 
no oxalic acid, but that they bore a striking resemblance to benzoic se'i 
Indeed eoiiie of the reactions are the same as those of benzoic acid, Mi ‘ 
was only after having submitted it to an cJcmentTry analy^s that tbeca® 
convinced that it was not benzoic acid. I shall call it ulharic acid, 
the following properties:— 
Its tMte is acid. When heated on platinum foil it melts and biira* 
smoky flame, leaving no residue, V’lien heated in a tube it is comiJeW,' 
VO atihzed, without leaving the least residue. The vapours condens! in w 
colder parts of the tube, forming long white needles. This sublimate 
however m composition from the acid itself, and I shall therefore call 
alizanc ncul. When heated in a tube with caustic lime it is decoraposolw^ 
a yellow oi distils over, having a smell very nearly resembling thatofbw»' 
It IS soluble in boiling water; the solution has an acid taste atid reiM^ 
litmus paper. A concentrated boiling solution crystallizes on cooling- “ 
IS ®®sily soluble m alcohol. Concentrated sulphuric acid dissolves it« t*' 
the solution no blackening takes place, and 
solahlp^in* ^y*^r.“**^* crj’slallizes on the cooler parts of the tube. It 
addit L ^ alkaline Liution gives crystalsoa- 
T. «fi f Tlie solution in ammonia gives noF^np^ 
be added ‘o the snlutiou in water;^ 
lime Rah ^ ^ oflervesconce has ceased, the solution gives a ci^^ 
ta ed in Is deoomposed^oa being 
Mhich „„ 
of iron n vr,ii« S aqueous soluUoii gives With perciu 
witrn trX r'fprecipitate, with sugar of lead a white 
white S n P'*P“Pitate, but on tlie addition of 
action will? vvhjch after some time becomes cjyslalline- 
thirebv nr wT*’ distinguishes it from benzoic add, whielij;^ 
also in water and 
the resemWaiinrt**^ characteristicH; but in most respects it will be ^ 
-j . I’^^tween the two is verv strilcino Tt is very probable 
quaiuity of '"‘''"ed from alizarin by means If nitric acid, but tii« ■ 
