All 6 Uses of

positive
in
The Adventures of Sherlock Holmes

You have heard me remark that the strangest and most unique things are very often connected not with the larger but with the smaller crimes, and occasionally, indeed, where there is room for doubt whether any positive crime has been committed.
Chpt 2

positive = certain

She became restive, insisted upon her rights, and finally announced her positive intention of going to a certain ball.
Chpt 3 *

positive = absolute (used for emphasis)

You shave every morning, and in this season you shave by the sunlight; but since your shaving is less and less complete as we get farther back on the left side, until it becomes positively slovenly as we get round the angle of the jaw, it is surely very clear that that side is less illuminated than the other.†
Chpt 4

positively = with certainty

This dust, you will observe, is not the gritty, grey dust of the street but the fluffy brown dust of the house, showing that it has been hung up indoors most of the time, while the marks of moisture upon the inside are proof positive that the wearer perspired very freely, and could therefore, hardly be in the best of training.
Chpt 7

positive = certain

Still, of course, one can't refuse a lady, and such a very positive one, too.†
Chpt 4

Definitions:

(1) (positive as in: I'm absolutely positive!)
certain (having no doubt; or used for emphasis)
(2) (positive as in: had a positive effect)
good or beneficial
(3) (positive as in: positive feedback from my boss)
approval or agreement
(4) (positive as in: a positive attitude)
optimistic (expecting or focusing on good things); or agreeable
(5) (positive as in: The test came back positive.)
found a condition or substance to be present
indicating the presence of something being tested for -- especially a disease, condition, or substance
(6) (positive as in: a positive number)
greater than zero (of a number)
(7) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

See a comprehensive dictionary for less common meanings of positive including some in the fields of electricity, physics, chemistry, medicine, philosophy, and grammar. Note that most all senses of positive indicate that something is good or present.