Here are the passages I though were interesting in this section of "A Study in Scarlet"
(Chapter 7) "The dog continued to lie stretched upon the cushion, breathing in a laboured way, but apparently neither the better nor the worse for its draught.
Holmes had taken out his watch, and as minute followed minute without result, an expression of the utmost chagrin and disappointment appeared upon his features, He gnawed his lip, drummed his fingers upon the table, and showed every other symptom of acute impatience. So great was his emotion that I felt sincerely sorry for him, while the two detectives smiled derisively, by no means displeased at this check which he had met.
'It can't be a coincidence,' he cried, at last springing from his chair and pacing wildly up and down the room; 'it is impossible that it should be, a mere coincidence. The very pills which I suspected in the case of Drebber are actually found after the death of Strangerson. And yet they are inert. What can it mean? Surely my whole chain of reasoning cannot have been false. It is impossible! And yet this wretched dog is none the worse.'"
I like this passage because it shows how Holmes deals with frustration, and the possibility of his reasoning being wrong, something he is very unused to. Also, Watson states in his narration "So great was his emotion that I felt sincerely sorry for him" which is interesting for us because he seems like such the emotional robot, only excited when he discovers something, and quietly depressed when he has nothing to do.
(later in chapter 7) "'Gentlemen,' [Holmes] cried, with flashing eyes, 'let me introduce you to Mr. Jefferson Hope, the murderer of Enoch Drebber and of Joseph Strangerson.'
The whole thing occurred in a moment - so quickly that I had no tie to realize it. I have a vivid recollection of that instant, of Holmes's triumphant expression and the ring of his voice, of the cabman's dazed, savage face, as he glared at the glittering handcuffs, which had appeared as if by magic upon his wrists. For a second or two we might have been a group of statues. Then with an inarticulate roar of fury, the prisoner wrenched himself free from Holmes's grasp, and hurled himself through the window. Woodwork and glass gave way before him; but before he got quite through, Gregson, Lestrade, and Holmes sprang upon him like so many staghounds. He was dragged back into the room, and then commenced a terrific conflict."
This passage also interests me because of the utter surprise that Holmes gives them all, then an almost time slowing effect as they all just stand and stare at Holmes and Mr. Hope. Then Mr. Hope realizes he's been caught and tries to run for it, but is once again caught by the three men.