All 10 Uses of

positive
in
The Mill on the Floss

—and young Guest so very fascinating; and, they say, he positively worships her (to be sure, that can't last!)†
Chpt 7.2 *

positively = with certainty

And he had really given himself the trouble of recommending Mr. Stelling to his friend Tulliver without any positive expectation of a solid, definite advantage resulting to himself, notwithstanding the subtle indications to the contrary which might have misled a too-sagacious observer.†
Chpt 1.3

Tom was only thirteen, and had no decided views in grammar and arithmetic, regarding them for the most part as open questions, but he was particularly clear and positive on one point,—namely, that he would punish everybody who deserved it.†
Chpt 1.5

His first impulse was to give a positive refusal, but he was in some awe of Tom's wishes, and since he had the sense of being an "unlucky" father, he had lost some of his old peremptoriness and determination to be master.†
Chpt 5.2

Not when that girl is as tranquil-hearted as Lucy, thoroughly possessed with a belief that she knows the state of her companions' affections, and not prone to the feelings which shake such a belief in the absence of positive evidence against it.†
Chpt 6.6

The very fact that he feared and half expected it would be sure to make this thought rush in, in the absence of positive proof to the contrary.†
Chpt 6.7

She moved her arm from the table, urged to change her position by that positive physical oppression at the heart that sometimes accompanies a sudden mental pang.†
Chpt 6.7

But to minds strongly marked by the positive and negative qualities that create severity,—strength of will, conscious rectitude of purpose, narrowness of imagination and intellect, great power of self-control, and a disposition to exert control over others,—prejudices come as the natural food of tendencies which can get no sustenance out of that complex, fragmentary, doubt-provoking knowledge which we call truth.†
Chpt 6.12

Uses with a meaning too rare to warrant foucs:

"And after all," he went on, in an impatient tone, trying to defeat his own scruples as well as hers, "I am breaking no positive engagement; if Lucy's affections had been withdrawn from me and given to some one else, I should have felt no right to assert a claim on her.†
Chpt 6.11

She is very pitiable; but then there was no positive engagement; and the air at the coast will do her good.†
Chpt 7.2 *

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.