On Animal Fluids. 295 



which belong to a particle of matter belong to the whole 

 mounfaiii of the same substance." True; but I know no- 

 thing of the properties of substances but \'y means of the 

 external sen-es (this indeed is an axiom); and unless the 

 particle be of a due magnitude, my organs of sense cannot 

 inform me in its properties. My honourable adversary 

 talks of the advantages of a small scale of operations in 

 the points of ceconomy and convenience. Granted — but 

 these are minor considerations indeed, to the acquaintance 

 with properties or acquirenjcnt of knowledge. When Dr. 

 Marcet also speaks of the advantage in point of accuracy, 

 I protest against it for reasons above explained. It is 

 further represented that there is a degree of " neatness 

 gained by reducing the scale of operations." I own I have 

 difficulty to conceive a just sense in which this term may 

 be employed on this occasion. Docs it mean the avoiding 

 extraneous things occurrinii in operations ? If so, I cannot 

 separate it from nccuracy ; ami as it is seldom practicable 

 to operate without meeting with some extraneous matter, 

 or " dirt," it appears to me that many of those old che- 

 mists who are reproached for mentioning " a little dirt" in 

 their results are nioje accurate than those modern chemists 

 who make up a " 77c«<" tabular exhibition of the consti- 

 tuents of substances in centesimal quantities which they 

 have never weighed, and even of which substances there 

 is a palpable detieiencv of proof, li' hy neatness be meant 

 the instruments employed, it would be as injudicious to 

 prefer neatness to knowledge, as euphony of style to per- 

 spicuity. 



A proud list is displayed of discoveries achieved by 

 microscopic experiments, or on small masses of matter ; 

 but that was needless. I never disallowed the utility of 

 such experiments. My plain answer is thi,s — that for cer- 

 tain purposes all the knowledge that is w^anted is attainable 

 and most easily by operations on the small scale — that such 

 is the nature of our present instruments, that it is only 

 practicable to work on small quantities of some kinds of 

 matter — that on almost all occasions it is advantageous to 

 commence an intended perfect investigation with experi- 

 ments on small masses, in order to enable the mind to in- 

 vent suijsequent experiments and perform decisive opera- 

 tions on large quantities. As to the successful practice* 

 referred to, ihcv only manifest that much may be acconj- 

 plishcd witii inferior means ; but it is demonstral)lc that tlie 

 same persons could have attained infinitely n)ore by su- 

 perior iuitrumcnls and in the more iavourable circum- 



6taacc« 



