274 0* 1 f fo Eff e 8 °f Mordants 



the rule everyday On the 15th of Prairi.d at noon,Delambre 

 arrived at the cyiinuer of copper, forming the other extremity 

 of the bafe, under the fignal of Lieufaint ; the extremity of the 

 laft rule was found to p.ifs the centre jull 4S! lines; and this 

 deducl. on being made, ss well as all the neceffary calcula- 

 tions, the refu.t wis a length of 6075,7^4689 toifes. 



Though thefe derate are fufficient to enable the reader to 

 judge of the great precifion employed in this operation, De- 

 lamhre added many other ingenious and nice precautions 

 ■which are too long to be repeated here, and which enfured 

 to his labour the highelr degree of exactnefs poflible. We 

 fliall only add, thit, by the accuracy of the initruments and 

 methods employed, errors of inches and feconds are as little 

 to be prefumed in the prefent meafurement, as errors of 

 toiies and minutes were formerly This great perfection is 

 chiefly owing to the labours of Borda. 



VIII. Ctiemical Rifle Jions on the Effect produced ! y Mordants iff 

 dyei'g Cotton red. By. J. A Chaptal. From the An- 

 nates dc Chimie, Vol. XXV L 



JN regard to the beautiful ted colour given to cotton by 

 means of madder the cafe is the fame as with cctain phar- 

 maceutic preparation', tne ridiculous receipts for preparing 

 which have been hi.herto refpecled, becaufe apprehenfions 

 have been ent named that their effect would be altered by 

 introducing the tealt change in the procefs. A month's la- 

 bour would fcarcely be fufficient to terminate all the opera- 

 tions which have been judged indifpenfibly neceffary for ob- 

 taining that beautiful colour called the Turkey or Adri- 

 anople red. Soda, oil, galj nuts, fumach, the fulphate of 

 alumine, blood, the gaftric Hour, madder, foap, the nitro- 

 muriate of tin, are employed in fucceflion. The true means 

 of Amplifying t' is procefs is not to labour at hazard, and to 

 make trial of the different methods pra&ifed without a 

 5 . £ uid< 5 



