Mr. Rupp’s Reply to Mr. Tennant. 
Turces bellum non amplius indicimus ne fu- 
perbos nos prebeamus. Regibus officia nof- 
tra & fecuritatem offeramus.. Artium & fei- 
€ntiarum folummodo amatores fumus. 
6¢ WALTIMORE.” 
66 Datum ex Mufeo, L. A. G& S.” 
ae 
To the Editor of the Monthly Magazine. 
SIR, 
\ Af ¥ obfervations on Mr. TENNANT’S 
M bleaching liquor, were made upon 
the fpecification of his patent, fuch as I 
Found it fiated in your Magazine for Merch. 
By that flatement it appears to me, that 
the falt in the receiver is a neceffary in- 
gredient ; nor could it be imagined, that 
Mr. TENNANT would incumber his pro- 
cefs with fo heavy an expence, if he had 
not found it indifpenfible. But as Mr. 
TENNANT aflures us, in his letter of the 
13th June, ** that the falt is zow recu- 
larly omitted, mere agitation being found 
pertectly fufficient ;°’ my objection to his 
diquor, 1 point of expence, is removed ; 
and I acknowledge, with pleafure, that 
Mr. TENNANT’s procefs, in its improved 
ftate, is a valuable difcovery. ‘The mat- 
ter being confidered as it ought to be, in 
this point of view, it cannot be juftly 
faid that my conclufion was too halty, 
and calculated to miflead the public. 
I agree with Mr. TENNANT, that, in 
order to bleach coloured goods chemically, 
it is proper to add alcaline falts to the 
oxygenated muriatic acid; but I cannot 
admit that the acid fhould be faturated. 
The proportion of alcali, mentioned in 
my obfervations on Mr. TENNANT’s pa- 
tent, is the fame with that which I ftated 
in another place, where it would have 
anfwered my purpofe to affign a larger 
portion, if truth had permitted it. I 
do not doubt but a greater quantity of 
aleali is employed by fome bleachers ; 
but there is no oecafion for it; and com: 
piete faturation would entirely deftroy 
the bleaching power of the acid. The 
experiments by. which I proved that the 
oxygenated muriatic acid: lofes its power 
in proportion ay it is neutralized, are be- 
fore the public, who will judge of their 
validity. Thofe celebrated chemifts, Mr. 
WatTr and M. BERTHOLET, made 
ufe of the fame methsd to afcertain the 
ftrenoth of the bleaching liquor; and the 
quantity on which I operated, was fuffi- 
ciently large for accurate inveftigation. 
But though the bleaching vf coloured 
ftuffs may require a partial nevtralization 
oi the acid, white goods, and thofe def- 
tined tor dying and printing (ani thefe 
appear more than three-fourths of the 
a 
produce of the manufacture), do not only 
require it, but are better acapted to the 
fubfequent procefles of dying and print- 
ing, when they are bleached with the pure 
oxygenated acid ; nor is there any danger " 
in the ufe of it, when it is properly ma- 
naged.' This I have afcertained by my 
own experiments. Mr. TznNANT’s ob- 
jection to the ufe of the apparatus, de- 
{cribed in the 5th vol. of the ‘* Manchef- 
ter Memoirs,” (viz. that a bleacher can- 
not calculate fo exaetly as to have exhaufted 
the acid every time he finds it neceflary 
to remove the goods from its action, and 
that there is no other way of preventing 
the efcape of the gas, whenever this oper- 
ation becomes neceffary), is eafily an-_ 
{wered. A few days experience will 
teach a perfon, of cominon underftanding, ~ 
to adapt the quantity and ftrength of his 
liquor to the quantity of goods he has to 
bleach, fo nearly, that the liquor, after 
the operation, if not exhaufted, will be fo 
weak, that hardly any gas will efcape 
during the fhort interval of time which 
a change of goods requires. It is, more- 
over, probable, that every bleacher would 
have occafion to employ two or more 
machines for his bofinefs, which being 
placed one higher than the other, the li- 
quor which has ferved in the higher may, 
if not exhaufted, be drawn into the lower 
apparatus, without inconvenience, or any 
fenfible lofs. 
‘It is a known fa&t, that a decoétion of 
madder, and other dyeing materials, will 
precipitate lime from its folution im acids. 
Dyers and princers alfo know to their 
coft, that lime will obftinately adhere to 
cotton ftuits. Frem thefe faéts I infer- 
red that there might be danger in the 
ufe of the cxymuriate of lime, in bleach- 
ing goods deftined for dyeing or printing. 
Time and experience will fhew whether 
my fufpicion is well or ill founded. The 
enlightened chemift will appreciate, as he 
ought, Mr. TENNAN’’s {heer at chemical 
theory. As he’ affetts to defpife theory, 
it will net be uniair to inquire, whether 
he made his difcovery by a judicious ap- 
plication of the theory and principles of 
chemiftry ? or whether. he, like many 
ethers, is indebted to fome lucky acci- 
dent? 
[think it my duty to ftate, that feve- 
ral refpectable bleachers’ in this. neigh- 
bourhood have made triabef Mr. TEn- 
NANT’s proceis, of which they {peak in 
favourable terms.’ Iam, ‘fir, 
Your moft obedient fervant, 
- THeo. Lewis Rupp. 
Mancheffer, Fulj 12,4798. ‘ 
bane te -) 
