30 CORRESPONDENCE Anal. PYOC. Correspondence Correspondence is accepted on all matters of interest to analytical chemists. Letters should be addressed to the Editor, Analytical Proceedings, The Chemical Society, Burlington House, London, WIV OBN. Oil and Fat Extraction Sir, time factor in the investigation concerned. I have duly read the reply of Dr. Hersch- Moreover, although he now states that the doerfer (Proc. Anal. Div. Chem. SOC., 1979, 16, methods recommended in this Report are 312) to my trenchant criticisms (Proc. Anal. intended to be used as reference methods, the Div. Chem. SOC., 1979, 16, 276) and note his heading of the Report clearly indicates that it is admission of the subordinate part played by the concerned with general methods, there being noJartuary, 1980 PUBLICATIONS RECEIVED 31 suggestion that it is intended for reference purposes only.Further, let me emphasise that our method, which goes unmentioned, combines time with reliability, as the Sub-committee members would have realised had any of them made comparative time tests as we did originally on cocoas with a maximum fat content of 24%. Accepting the fact that my two fellow APA members approved every word of the Report, I draw my own conclusions accordingly. Re- garding the late Dr. Pearson, with whom I had much friendly professional correspondence, I would say that he, being dead, yet speaketh on page 13 of the 6th Edition of “The Chemical Analysis of Foods,” where he obviously enter- tains no doubt whatsoever regarding the efficiencies of the successors to the outdated Soxhlet apparatus, pointing out that, with them, estimation can be completed in a much shorter time than with the preceding form of fat extractor. To bring the year forward from 1945 to 1961, let me quote from the supplements page (S11) in the APA Bulletin for that year, in which I cite my figures for the oil content (before and after grinding) of a sample of meat and bone meal, 1Q h total extraction time being proved sufficient : Oil extracted by light petroleum Before grinding .. 5.3% 5.5% 5.7% 5.7% After grinding . . 5.9% 5.9% + h l h 1&h 2 h By reason of its high level of efficiency our method is, incidentally, in use in various labora- tories, Avon, Lancashire, West Yorkshire, Newcastle and BFMIRA being amongst them. Moreover, perhaps it would not be too much to infer that the preference for copper(I1) sulphate as against mercury(I1) oxide as the catalyst in the determination of nitrogen stems from the comparative determinations conducted by me in Leeds in 1956, published first for limited circulation and later in J .Ass. Publ. Anal., 1976, 14, 29. (Former Public Analyst and Oficial Agricultural Analyst for the Cities of Leeds and Wakefield) “I’ey”, 3 Great Brockeridge, Westbury-on- Trym, Bristol, BS9 T Y3 C. H. Manley Sir, I see that the question of the merits of different kinds of oil extraction apparatus is again leading to public correspondence. More because I like to support Mr. Manley’s oft- repeated insistence on the merits of the hot solvent extraction, that his apparatus affords, than from any wish to comment on the delibera- tions made about fish products, I find myself just raising my eyebrows at Dr.Herschdoerfer’s bland assurance that all members of his Sub- Committee approved every word of a particular report. The great snag with democracy in science is that people who sit on committees do get tired, and after a while those who work a t the bench tend to succumb to those whose life is spent in committee, yielding in effect to the philosophy, “What they say is good enough.” One is reminded of Lewis Carroll’s comment about there being nothing like hay for a cold. Alice, everyone will remember, was told that this did not mean that there was nothing better! The statement as it stood was correct. Committee documents have a way of following the same reasoning. In these days of published EEC methods of analysis, all of which must have been approved by committees, and which cheerfully re-hydrolyse already hydrolysed material, or direct opera- tives to do such things as pipette concentrated sulphuric acid, one finds oneself at odds with the concept of arriving at scientific truth by vote. Collaborative studies in recent years have almost destroyed my faith in the idea that analytical chemistry is an exact science, and I suspect that curiosities get into committee- approved methods of analysis, because results that come together towards agreement as participants become more familiar with a pro- cedure also follow changes of words that happen to have been made in the most recent committee meetings. It is Post hoc-Ergo propter hoc (whatever that means). A. C. Bushnell County Analyst, Lancashire County Council, County Laboratory, County Hall, Preston, PR1 8XN There is a lot of it about.