The image of a star or planet, then, formed by a single lens cannot be optically perfect; instead it will be a confused intermingling of images of various colors.
Optically it was always a puzzle, but photographs by Roberts of England first revealed the true spiral, with ringlike formations partially distinct, and knots of condensing nebulosity as of companion stars in the making.
Optically biaxial crystals in which there is no fixed and definite relation between the optical and crystallographic directions--corresponding with the anorthic system.
In 1818 Sir David Brewster found that crystals could be divided opticallyinto three classes, viz.
Optically uniaxial crystals--corresponding with the tetragonal and hexagonal systems.
Like the solutions of certain optically active organic substances, such as sugar and tartaric acid, some optically isotropic and uniaxial crystals possess the property of rotating the plane of polarization of a beam of light.
If the ordinary index of refraction be greater than the extraordinary index, the crystal is said to be optically negative, whilst if less the crystal is optically positive.
Optically biaxial crystals in which only one of the three principal optical directions coincides with a crystallographic axis--corresponding with the monoclinic system.
The several symmetry-classes of each system are optically the same, except in the rare cases of substances which are circularly polarizing.
Some other substances which crystallize in enantiomorphous forms are, however, only "optically active" when in solution (e.
For up to that time it had been supposed that such grouping in occasional pairs or triplets was chance coincidence, the two being optically foreshortened together, but having no real connection or proximity.
The answer is neither ready nor complete, but our own eyesight shows how much may be accomplished by means of instruments far from optically perfect.
But the compound eye is not optically constructed so as to render possible the formation of continuous images.
I think it must be regarded as a crowning piece of evidence both of the correctness of Professor Lister's views and of the impotence, as regards vital development, of optically pure air.
How will he account for the absolute immunity of a liquid exposed for months in a warm room to optically pure air, and its infallible putrefaction in a few days when exposed to dust-laden air?
At the beginning of this experiments the shade was charged with floating matter; at the end of half an hour it was optically empty.
With this view, I place before my friend and co-enquirer two liquids which have been kept for six months in one of our sealed chambers, exposed to optically pure air.
At the end of a week the chamber was optically empty, exhibiting no trace of matter competent to scatter the light.
The air which they found inoperative was proved by the luminous beam to be optically pure and therefore germless.
For a moment the tube was optically empty, nothing whatever being seen within it; but before a second had elapsed a shower of particles was precipitated on the beam.
On sending the beam through this mixture, the tube, for a moment, was optically empty.
The phrase 'optically empty' shows that when the conditions of perfect combustion were present, the floating matter totally disappeared.
An experimental tube in this condition I call optically empty.
The inference just referred to is completely disposed of by the simple question: 'Why, when your sterilised organic infusion is exposed to optically puree air, should this generation of life de novo utterly cease?
The other constituents are fragments of semi-vitreous basic rocks and of palagonite, together with fragments of plagioclase and pyroxene crystals and of an amorphous siliceous mineral which behaves optically like chalcedonic silica.
I have tried many other plans; indeed the possible methods ofoptically superimposing two or more images are very numerous.
I may mention a plan which had occurred both to Mr. Herbert Spencer and myself, the principle of which is to superimpose optically the various drawings, and to accept the aggregate result.
It isoptically inactive, and readily soluble in 1.
In thin sections it is translucent and optically isotropic, and recent examinations seem to prove that it is a homogeneous mineral and not a mechanical mixture of chrysocolla and limonite.
One line, in the yellow green, is so dominant optically as often to be described as the auroral line.
Again, put yourself in the hands of an optically inclined friend, and let him operate upon you thus.
They are either optically so owing to their accidental situation in the heavens, or physically near each other in space, and one of them revolving round the other.
The successful resolving of racemic leucodigallic acid into both of its optically active components can only be brought about through the d- or l-hexacarbethoxyleucodigallic acid on introducing the latter into a 1 per cent.
The total solubles must be determined by the evaporation of a measured quantity of the solution previously filtered till optically clear, both by reflected and transmitted light.
A very important characteristic of the action of yeast on the amino-acids is that the two stereo-isomerides of theseoptically active compounds are fermented at different rates.
The fractional hydrolysis ofoptically inactive esters by lipase Part II.
Their solutions in water are faintly alkaline, optically active, and laevorotatory.
The solution is optically active and laevorotatory, but with very variable specific rotation.
What is needed is that the product should make a sol or gel which to the naked eye appears to be opticallyclear both to reflected and to transmitted light.
In other words, the same number of molecules of the optically active substance in solution will always produce the same rotatory effect.
Solutions of nucleic acids areoptically active, probably because of the carbohydrate constituents.
Most of the alkaloids contain asymmetric carbon atoms and are, therefore, optically active, usually levorotatory, although a few are dextrorotatory.
These observations upon some of the earlier known forms of optically active organic acids led the way to a general study of this phenomenon as exhibited by the optically active soluble carbohydrates.
As has been pointed out, solutions of invert sugar become optically inactive when heated to 82 deg.
All solutions of plant proteins are optically active, rotating the plane of polarized light to the left, in every case.
What, in such circumstances, would be the aspect of the scene, optically exhibited from some point in space elevated a few hundred yards over the sea?
It has been found that tridymite becomes optically uniaxal at a moderate temperature, and its general characters appear to be essentially identical with those of asmanite.
The occurrence of hemihedral faces was considered by Pasteur to be a sufficient criterion for an optically active substance.
As has already been mentioned, this behaviour is found in the case of optically active isomerides, the solubilities of which are identical.
Examples of such systems will no doubt be found in the case of optically active substances, where both isomerides are apparently quite stable at the melting point.
The behaviour of sodium ammonium racemate is of interest from the fact that it was the first racemic substance to be resolved into its optically active forms by a process of crystallization.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "optically" in a variety of sentences. We hope that you will now be able to make sentences using this word.
