JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS because the left eye is better than the right. In the instance, of course, of a rifle the choice depends on the left- or right-handedness of the individual and may, therefore, demand the use of the poorer eye. The training of the eye to observe, that is to be able to see all the detail and by looking to discern subtle differences which, passed on to the brain, enable inferences of form, quality, colour and all those properties of matter which are intrinsic attributes can only be achieved by practice. Perhaps of all the common instruments used in the laboratory, the microscope is the one which epitomises this point. Perhaps, too, the microscope is the one which is most used with faulty technique. It is somewhat outside the scope of this talk to discuss microscopy--certainly there is no time--but it will suffice to say that if the microscope be employed as a scientific instrument and not merely as a magnifying glass, and the principles on which it works are known, then the observant looker will discern things which are over- looked by the gazer, and an appreciation of quality and form will be carried to the brain. Wrongly used the eye will detect artefacts the trained eye will distinguish them from reality. Perhaps it would be permissible here to draw attention to the use of the simple magnifier. If such a "microscope" is to be used--and they are extremely useful beware of buying one which magnifies too much. Don't buy one which enlarges x 10, 12 or 20. Get one x 6 or x 8, and make sure it is aplanatic and achromatic. High magnification prevents one from seeing the wood for the trees. In the same way always use the lowest power of a microscope which will enable the detail to be seen. To revert to the opening paragraph. It will be apparent that "looking" at a cream by spreading it over the back of the hand, the expert watches the way it rubs into a thin film. Note is taken of the ease of spreading, whether it liquefies or not, whether aeration has occurred during manufacture or arises because the film entrains air. If the cream is a pigmented one, do the particles streak or are they gritty so that they protrude out of the film. Does the i51m dry too quickly or does it remain too long on the skin. Some- times creams "roll," a property which is nearly always quite undesirable. In all these and many other effects, the eye passes the message to the brain and it gives a reliable assessment of quality. It is, of course, true that in addition to the message from the eyes, the sense of touch has also contributed towards the final judgement. Looking can mean more than a visual or optical method. One can look at things, thoughts and living creatures with one's eyes shut. Very often it is a good plan, although it often requires great courage, to look at oneself. This particular mode of looking can be very illuminating, although taken too far it may lead to such serious introspection that its consequences may completely override its benefits. Be that as it may, the essence of looking at anything depends on whether the looking gives a guide to answering one or more of these questions: 152

LOOKING AT THINGS How? When? and Why? In looking at a piece of mechanism the eye should enable the "how" to be appreciated. This process is a sort of differentiation. The reverse process-- a sort of integration--is when a problem has to be looked at from the end- point to the means. Packaging problems often come under this heading, and like integrals, can be completely solved only when the differential is known. For example, a cardboard box is to be made. It is known that if a thin card is folded over and pressed, the fold can be straightened out so the cardboard is more or less flat, but on applying a slight sideways pressure the fold will re-form. Because this is known it becomes easy to see the mode to be employed in fabricating a folding carton. Many other ways have been found for producing an incipient fold, e.g., scoring, and because of this it becomes possible to construct mechanical devices to enable folding cartons to be made. Many such problems can be worked out in the brain, but they are almost wholly dependent on having seen similar things by means of observant eyes. And the problems need not be mechanical ones. Let us take a method of analysis for control purposes in a product the composition of which is known. It will undoubtedly be true that an extensive time-consuming assay can be drawn up which will give the right answers. But for control purposes it would mean delay in production. A shorter but sufficiently accurate estima- tion is needed. To do this the whole product and method of manufacture must be looked at. First of all, the point has to be cleared up as to whether the specified ingredients are present. This is best accomplished by making sure that they are up to standard as soon as they are delivered into the factory. If their quality be right, then they have to be weighed out correctly and put into the mixing vessel. This is best done by the foreman checking the weights, initialing the process sheet and watching the various additions. If this routine is followed the composition should be correct, but a final means of assessment is necessary. This is when the looking starts. If the product is a cream then it should have certain physical attributes which will characterise its quality. According to each individual firm's product these particulars will be or should be known and should be easily identifiable. It may be colour, opacity, consistency or body, aeration or non- aeration, easy of liquefying, etc. Most of these are susceptible of quick tests which can be made objective instead of subjective. Colour can be matched in a comparator or tintometer. More exact assays, which in certain products are imperative, can be done by the more expensive photo-electric photo- meters. Opacify is best assessed by a simple photo-electric device, the per- centage of light passing through a thin film of precise thickness being meas- ured. Such a film can be obtained by the use of the Lovibond method in which an optical flat with three accurately ground "legs" is superimposed on a plain flat. Films of 0.25, 0.50 and 1.00 mm. can be obtained. The extent of 153