328 Substitution of Oxymwiaie of Magnesia 



ti\t\on } None are even offered, except the harmless nature 

 of the resuliing muriate of magm-sia. Muiiaie of lime is 

 declared to be injurious, on the evidtnce cit experiment^ 

 which do not su-cceed in the hands of others ; and the 

 bleachers deny the fact altogether. It is certain that many 

 pieces are found to be d^unaged by bleaching with the oxy- 

 muriale of lime; but this ii universally known to be pro- 

 duced by negligence or ignorance^ and not by the causticity 

 of the resultincf muriate. 



But although, in Sir II. Davy's experiment, the " very 

 Strong solution of muriate of lime" did " considerably 

 weaken" the linen, how is the fact connected with the pro- 

 cess of the bleacher, who never makes use of any other 

 than weak solutions ? — Certainly not at all, unless a 

 mode of reasoning be introduced which has been attributed 

 to Sir H. Davy, namely, that " if a strong solution act 

 energetically, a weak one must act proportionately so :" 

 but as this kind of argument has been disclaimed, I am far 

 from insisting on the matter: hence the above question re- 

 mains to be answered. 



Now although Sir H. Davy does not appear to have been 

 aware of it, there certainly is an advanlasic in oxvmuriate 

 of magnesia, if that substatice could be obtained at even a 

 reasonable price ; namely, in bleaching calico destined for 

 printing, btfore it comes into the hands of the printer. 

 After the immersion of the calico, according to the usual 

 process, in oxvmuriate of lime, the vvorkinen are some- 

 times so negligent as nut perfectly to wash otit the muriatii; 

 so that, during the souring, a sulphate of lime is precipi- 

 tated into liic substance of the cloth, which cannot be re- 

 moved without more washing and trouble, than usually is, 

 or can well be, bestowed on it. This sulphate acts as a 

 mordant to certain colours used in the subsequent pro- 

 cess of printing, and occasions a dulness of those parts 

 which should be of a clear white ; and perhaps makes the 

 delicate snade? of colour sotnewlial different from what was 

 intended. 



It is no wonder that neiTiigence in this, as well as in every 

 other case, should be productive of inconvenience: when 

 the workmen do their duty, nothing disagreeable can result 

 fror!i the abovementioned causes. 



With a view of guarding against negligence, theoxymu- 

 riate of magnesia certainly possesses advantages ; for even 

 should the resulting muriate be not perfectly washed out, 

 the sulphate formed during immersion in the sours is so so- 

 luble 



