124 
UEPORT—1847. 
the solution deposits after some time red flocks. It dissolves in caustic alkalies 
with a reddish-purple colour, and is reprecipitated by acids in yellow flocks. Tie 
solution in ammonia gives with tbe chlorides of calcium and barium dirty red 
precipitates. The alcoholic solution gives with an alcoholic solution of sagai 
of lead a dark red precipitate. If Into the boiling alcoholic solution hydrate 
of alumina be introduced, the alumina acquires an orange colour, and lie 
fluid is deprived of all its rubiacin. The compound with alumina thus formed 
dissolves entirely in caustic potash, forming a purple solution, a chanictcriaic 
which disfjngmshcs it from alwarin, the alumina compound of which, « 
mentioned above, is insoluble in caustic potash. 
The aqueous and alcoJiolie solutions of rubiacin communicate a slight tinitr 
to mordanted cloth, the latter more timn the foroier. It seems to be intt* 
pableiteelf of dyeing, hut in conjunction with alizarin it assists in iheprocw 
ot madderMlyeing in a very essential manner, as I shall afterwards show. 
Rubiavic Acid .—I Jiave before described the method of obmining this 
acid through the instrumentality of the persalts of iron. There is w 
reason for supposing that it. exists aa such in the plant. It is doubtlesia 
product of tlie oxidation of rubiacin. To obtain it in a state of pnrity, pun 
crystallized rubi^atft of potash is disRolvcd in water, and muriatic-acid « 
any strong acid is added, w hich precipitate.'* the rubiacic acid in the shape rf 
a yellow powder. 1 1 has a pure lemon-yi’Jlow colour. It cannot be obtainfli 
111 a crysta line form. It i.s slightly soluble in 'iHiilmc water, to which it iin- 
parts a yellow colour. It is also slightly soluble in boiliug alcohol wiihi 
yellow colour. 1 he solution deposits nothing on cooling, but water prodticw 
in It an iridescont appearance, caused by the deposition of minute crystels 
V lien heated on platinum foil it lui-lts and burns witli a bright flame, leaving 
no residue. \\ hen heated in a tube it melts, and gives fuinc-s which coudinrf 
on the colder parts of tlie tubo to an oil which solidifies, but doe* not err* 
stallize. Concentrated sulpliuric acid dissolves it with ft yellow colour, and 
water precipitates it again in yellow flocks. On heating the aolution ifl siih 
pftunc acid it become* darker, but no gas is given off; some decomposition 
seems however to have takcu place in consequence of the heating, forwntei 
now produce no precipitate. Concentrated nitric acid dbsolre.* it on boiliw- 
and slowly deeompi^ it with an evolutiou of nitrous acid. It dissolves in • 
of iron witli a dark rcddlsli-brown colour, and is re- 
precipitated by acids in yellow flocks. It is not aftected by bichromate of 
po^h and sulphuric acid even on boiliug. 
to I as yet been able 
uppHIpa nnri* . ^ n liot coiicentmted solution in water m 
brick-red colour. On being heated it is inslaotlr 
blood fpd 1^' ^ The aqueous solulion has ■ 
transparent. The addition to it of caustk 
boilhir ®*suine a lieautiful dark purple colour, and a eoncentrat^ 
not^h T\ crystallize on cooling after the addition of cau-^ 
?alN f 11 ■ gives witii solutions of the earthy and nictaUsf 
colour.?/. reactions. With nhloride of calcium it gi^aaiiorsie 
tate wif’l, !?? ? «'ith chloride of barium a yeIlo^r pr^f^ 
colourpfl magnesia a yellow precipitate : witli alum an oranfo- 
with nrrr.hi.lv protosulplwte of iron a greenuih-gray precipi»tr; 
in the hniTn rfdilish-brown precipitate, which is soluU® 
copper a "'f". f H “ -■«* precipitate; with .uittate o' 
is not dinner, 1 K * '*’1*^*' '“tdite of silver a vellow precipitate, wliith 
'rith boif.ng; with protonitrate of mercury a yellow prn'ipita^; 
I rchlonde of mercury a crystalline, yellow precipitate; with prow 
